Implement Phase 7C local status dashboard

Add fixed status icons, OLED dimming and wake behavior, lowercase
glyphs, and access-point metadata tracking. Update validation guidance,
roadmap status, and provide an icon layout mockup with licensing.

docs/roadmap.md

@@ -37,7 +37,7 @@ These constraints apply across all phases:
 | 5A | Authenticated HTTPS administration foundation | **Complete** |
 | 5B | Offline xterm.js WebSocket serial terminal | **Complete** |
 | 6 | Authenticated SSH serial transport | **Complete** |
-| 7 | Local display and button interface | **In progress (7C)** |
+| 7 | Local display and button interface | **In progress (7D)** |
 | 8 | Security and production hardening | **Planned** |
 | 9 | Authenticated, rollback-capable OTA | **Planned** |
 | 10 | BLE serial transport and provisioning evaluation | **Planned** |
@@ -184,7 +184,7 @@ The order below is the current plan. Phase 7 is in progress; later phases remain
 
 Add a standalone local status/control interface without making it a dependency of the serial core. The planning baseline uses a 128×64 dual-color monochrome I²C OLED sold with an SSD1315 controller. Phase 7A confirmed SSD1306-compatible operation, 7-bit I²C address `0x3c`, orientation, column mapping, contrast/inversion behavior, button inputs, and the physical color geometry on the selected hardware.
 
-Phase 7A diagnostics and target-hardware electrical validation are complete. Phase 7B display-driver validation is complete; Phase 7 overall remains in progress (7C). Phases 7C through 7E are not complete.
+Phase 7A diagnostics and target-hardware electrical validation are complete. Phases 7B and 7C are complete; Phase 7 overall remains in progress (7D). Phases 7D and 7E are not complete.
 
 #### Hardware baseline
 
@@ -196,9 +196,9 @@ Phase 7A diagnostics and target-hardware electrical validation are complete. Pha
 - Hardware verification established yellow rows 0–15 and blue rows 16–63. A narrow physical black divider separates the two regions even though row 15 is the final yellow addressable row and row 16 the first blue addressable row.
 - Keep assignments centralized in the board profile rather than scattering display or button GPIO assumptions through UI code.
 
-![Proposed Phase 7 overview display](phase7_display_mockup.svg)
+![Phase 7C icon status-page mockup](phase7c_icon_mockup.svg)
 
-The persistent yellow strip is reserved for serial-service state, Wi-Fi strength, active USB/Web/SSH counts, current writer, total clients, and an alert indicator. Phase 7B must render it as a separate 128×16 status panel. The blue 128×48 content panel begins at row 16 and rotates through overview, RS-232, broker-client, and network/service pages; the physical black divider must remain visually clear. No password, Wi-Fi secret, private-key material, or routine credential data may appear on the display.
+The persistent yellow strip uses fixed-position serial, Wi-Fi-strength, USB, WebSocket, SSH, broker-client, and alert icons. Active icons are solid with a compact value below; inactive icon slots remain blank and show no value. The blue 128×48 content panel begins at row 16 and rotates through overview, RS-232, broker-client, and network/service pages; the physical black divider remains visually clear. No password, Wi-Fi secret, private-key material, or routine credential data may appear on the display.
 
 #### Implementation sequence
 
@@ -207,23 +207,25 @@ The persistent yellow strip is reserved for serial-service state, Wi-Fi strength
    - The selected module acknowledged at 7-bit `0x3c` (8-bit `0x78` write / `0x79` read). A guarded full scan is retained for the dedicated local-UI bus; an absent display remains nonfatal and does not make the serial core dependent on the OLED.
    - Hardware validation passed for geometry, orientation, row/column addressing, contrast, inversion, button pull-ups/debounce/short-press/long-press/stuck behavior, and the color geometry: yellow rows 0–15, blue rows 16–63, with a physical black separator between the regions.
 2. **Phase 7B — Display driver — Complete**
-   - The `local_display` service owns the local I²C bus, SSD1315-compatible panel, and framebuffer. It uses a static 1 KiB 128×64 framebuffer, a compact 5×7 uppercase/digit/punctuation renderer, and an internal mutex; do not add LVGL for this fixed monochrome UI.
+   - The `local_display` service owns the local I²C bus, SSD1315-compatible panel, and framebuffer. It uses a static 1 KiB 128×64 framebuffer, a compact 5×7 upper/lowercase, digit, and punctuation renderer, and an internal mutex; do not add LVGL for this fixed monochrome UI.
    - Rendering treats the yellow 128×16 status panel (rows 0–15) and blue 128×48 content panel (rows 16–63) as separate panels so the physical divider remains clear.
    - Frame commits refresh only dirty 8-pixel pages. I²C runs at 100 kHz with bounded transactions.
    - The display bus initializes at boot; a known display is automatically initialized and cleared. A missing or unresponsive display is nonfatal and does not make the serial core dependent on it.
    - Target-hardware validation passed for initialization, all display diagnostic patterns, the rendered panel layout and physical divider, row 15/16 boundary, contrast, inversion, display-off/reinitialization, and button diagnostics. Observed contrast control has a useful brightness range of 1–255.
-3. **Phase 7C — Read-only status UI — Implemented; validation pending**
+3. **Phase 7C — Read-only status UI — Complete**
    - The low-priority `local_status_ui` owner task builds display state from copied public serial, Wi-Fi, broker, USB, WebSocket, HTTPS, and SSH snapshots. It does not parse CLI output, reach into transport internals, or become a broker client.
    - Previous/back and next short presses navigate overview, RS-232/modem, broker-client/writer, and network/service pages. Select has no state-changing action in this read-only phase.
    - The task polls and debounces the existing active-low button inputs and refreshes at 4 Hz maximum. It collects service snapshots before beginning a display frame, so no service or broker lock is held across an I²C transaction.
+   - The yellow panel is page-independent and uses fixed icon slots. Wi-Fi strength is shown by segmented Wi-Fi bars; the USB glyph is derived from Pictogrammers Material Design Icons. Page text uses lowercase where appropriate, separates labels and values with colons, and shows the active station or AP SSID plus channel.
+   - To reduce OLED aging, inactivity dims contrast to `1` after five minutes and switches the panel off after ten minutes. The first debounced button press restores contrast `127` and wakes without navigating.
    - A missing/unresponsive display is nonfatal; the task remains read-only and never acquires serial writer ownership.
-   - Pending target-hardware validation: page navigation, each page's live snapshot values, concurrent USB/WebSocket/SSH operation while refreshing, and UART0 responsiveness.
+   - Target-hardware validation passed for the four pages, fixed active-only status icons, lowercase layout, diagnostics hold, dim/off/wake behavior, all available concurrent client interfaces, UART0 recovery, and serial traffic from 9600 through 230400 baud.
 4. **Phase 7D — Local controls — Planned**
    - Add a shallow menu for safe serial, Wi-Fi, HTTPS, SSH, writer-release, display, and reboot actions through direct service APIs.
    - Require a visible confirmation screen and a timed select hold before stopping active services, revoking a writer, rebooting, or performing another disruptive action.
    - A local display is not a serial broker client and cannot silently acquire the writer lease.
 5. **Phase 7E — Reliability, persistence, and documentation — Planned**
-   - Add contrast and optional dim/blank timeout settings to limit OLED burn-in without making the display necessary for recovery.
+   - Make the implemented contrast dim/blank timeouts configurable and persistent without making the display necessary for recovery.
    - Validate display removal, I²C NACK/timeouts, stuck buttons, queue saturation, and repeated actions.
    - Re-run concurrent USB CDC, WebSocket, and SSH traffic while the UI refreshes and confirm UART0 remains responsive.
    - Update wiring, electrical-test, command-reference, and recovery documentation.