[codex] Add map telemetry and LXMF fixes (without PNG tiles)

[brothercorvo]

Supersedes #20.

This PR carries the same functional changes as #20, but removes the tracked tiles/**/*.png payload from the review.

What changed

• keep the map, telemetry, TCP/LXMF, propagation, GPS, and message-state work from [codex] Add map telemetry and LXMF fixes #20
• remove all tracked PNG tile assets from the PR branch
• leave the code and submodule changes otherwise aligned with the original PR branch

Why

The PNG tile cache should not be reviewed or merged as part of the feature branch. Removing it makes the PR materially smaller and keeps the review focused on source changes.

Impact

Users get the same functional work proposed in #20, without bundling tens of thousands of cached tile artifacts into the diff.

Validation

• No functional code changes were made beyond removing tracked PNG assets from the branch.
• The replacement branch is based on the pushed PR 20 head plus a single cleanup commit.

[greptile-apps]

Greptile Summary

• Adds a live OSM tile map screen, GPS/peer telemetry over LXMF, staged WiFi reconnect, budgeted TCP frame processing with PSRAM ring buffer, and message sent/failed status indicators across MapScreen, TelemetryManager, TCPClientInterface, and UIManager.
• The received-locations load() loop lacks the MAX_RECEIVED cap check that the sessions loader has, allowing a corrupted SPIFFS file to bypass the 32-entry invariant. The _download_complete and _task_should_stop booleans are shared between the download FreeRTOS task and the main loop without volatile or std::atomic, which is formally undefined behavior under optimization.
• The North American DST bounding box includes Mexico, where DST was abolished in 2023, so Mexican users will receive an incorrectly applied +1h DST offset during what would have been summer months.

Confidence Score: 4/5

Safe to merge with minor fixes; no critical correctness or security regressions introduced beyond the already-noted prior-review items.

All new findings are P2 — the unsynchronized booleans are benign on ESP32 in practice, the location-load cap bypass requires file corruption, and the Mexico DST error is a cosmetic timezone inaccuracy. No P0/P1 defects were found beyond the carry-over issues from the previous review thread.

lib/tdeck_ui/Telemetry/TelemetryManager.cpp (missing load cap), lib/tdeck_ui/UI/LXMF/MapScreen.cpp (unsynchronized task flags), src/main.cpp (DST boundary).

Important Files Changed

Filename	Overview
lib/tdeck_ui/UI/LXMF/MapScreen.cpp	New map screen with 2×2 OSM tile grid, GPS marker, peer markers, and a FreeRTOS download task; _download_complete and _task_should_stop are unsynchronized booleans shared across tasks.
lib/tdeck_ui/Telemetry/TelemetryManager.cpp	New telemetry persistence layer; sessions load enforces MAX_SESSIONS cap but received-locations load does not, allowing corrupted SPIFFS to bypass the MAX_RECEIVED=32 invariant.
src/main.cpp	Major refactor: staged WiFi reconnect state machine, split persist cycle, GPS timezone logic with DST detection, message sent/failed callbacks, and propagation node migration; DST box includes Mexico where DST was abolished in 2023.
lib/tdeck_ui/Telemetry/TelemetryCodec.h	New encode/decode codec for Sideband/Columba telemetry over LXMF; skip_msgpack_value() helper correctly introduced and used in decode_columba_cease, but decode_telemetry still uses unpackNil() for unknown keys (flagged in prior review).
src/TCPClientInterface.cpp	Substantial RX pipeline overhaul: PSRAM-backed ring buffer with head-index, high/low watermark throttling, budgeted frame processing per loop, and chunked bulk reads replacing byte-at-a-time loop; looks mechanically sound.
lib/tdeck_ui/UI/LXMF/UIManager.cpp	Adds map screen integration, telemetry session management, send/failed message callbacks, deferred conversation-list refresh, and location sharing orchestration; LVGL lock discipline is consistent with the rest of the file.
lib/tdeck_ui/UI/LXMF/ChatScreen.cpp	Adds location-share GPS button with duration picker dialog and propagated-message delivery indicator; btns_sharing/btns_sharing2 arrays are dead code (previously flagged), otherwise clean.
lib/tdeck_ui/Hardware/TDeck/TileDownloader.cpp	New HTTP tile downloader with PSRAM buffer; TLS certificate verification is disabled (setInsecure), chunked responses are rejected, and MITM vulnerability exists (all flagged in prior review).

Prompt To Fix All With AI

Fix the following 3 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 3
lib/tdeck_ui/UI/LXMF/MapScreen.cpp:40-42
`_download_complete` and `_task_should_stop` are plain `bool` members written by the download FreeRTOS task and read/cleared by the main loop without any synchronization primitive. Without `volatile` or `std::atomic<bool>`, the compiler is free to cache the value in a register across iterations, so a write in one task may never be observed by the other. On ARM Cortex-M4 (ESP32) this won't tear in practice, but it is formally undefined behavior and a real risk if LTO or aggressive optimization is enabled.

```suggestion
    _download_complete.store(false, std::memory_order_relaxed);
    _download_task = nullptr;
    _task_should_stop.store(false, std::memory_order_relaxed);
```

### Issue 2 of 3
lib/tdeck_ui/Telemetry/TelemetryManager.cpp:312-316
The sessions load loop enforces `MAX_SESSIONS` with a break, but the received-locations load loop has no equivalent cap guard. A corrupted or manually crafted `/telemetry_locations.dat` with `count = 255` would push up to 255 entries into `_received`, silently bypassing the `MAX_RECEIVED = 32` invariant that `on_location_received()` maintains at runtime. Add the same check that the sessions loader uses.

```suggestion
            for (uint8_t i = 0; i < count; i++) {
                if ((int)_received.size() >= MAX_RECEIVED) {
                    WARNING("Telemetry: Reached location load limit, skipping remaining entries");
                    break;
                }
                ReceivedLocation r;
                uint8_t hash_len = 0;
                f.read(&hash_len, 1);
                if (hash_len > 32) break;
```

### Issue 3 of 3
src/main.cpp:374-377
The `uses_north_america_dst` bounding box (`latitude 24–70, longitude -127.5 to -52.5`) includes the bulk of Mexico, which abolished DST nationally in 2023 (most states stopped observing DST with the 2023 Energy Reform). Mexican users inside this box will have the M3.2.0/M11.1.0 DST rules applied incorrectly, giving them a +1h error during what would have been summer DST periods. A tighter southern boundary or a Mexico-exclusion check would prevent this.

```suggestion
static bool uses_north_america_dst(double latitude, double longitude) {
    // Mexico abolished DST for most states in 2023; exclude the Mexican interior
    // (roughly south of 29.5°N outside the US border zone) to avoid incorrect DST.
    if (latitude < 29.5 && longitude < -92.0) {
        return false;
    }
    return latitude >= 24.0 && latitude <= 70.0 &&
           longitude >= -127.5 && longitude < -52.5;
}
```

_{Reviews (4): Last reviewed commit: "Fix remaining PR 23 review findings" | Re-trigger Greptile}

[giu-Expedibox]

@torlando-tech branch is ready for your review