[feat](trx-wefax): implement WEFAX decoder with full server and frontend integration

Pure Rust WEFAX (Weather Facsimile) decoder supporting 60/90/120/240 LPM,
IOC 288 and 576, with automatic APT tone detection and phase alignment.

Core DSP pipeline:
- Polyphase rational resampler (48k→11025 Hz)
- FM discriminator (Hilbert FIR + instantaneous frequency)
- Goertzel tone detector (300/450/675 Hz APT tones)
- Phase alignment via cross-correlation on phasing signal
- Line slicer with linear interpolation pixel clock recovery
- Image assembler with PNG encoding

State machine: Idle→StartDetected→Phasing→Receiving→Stopping

Server integration:
- WefaxMessage/WefaxProgress in trx-core DecodedMessage
- DecoderConfig, DecoderResetSeqs, RigCommand wefax variants
- DECODER_REGISTRY entry in trx-protocol
- DecoderHistories/DecoderLoggers wefax support
- run_wefax_decoder() async task in trx-server audio.rs
- History persistence in pickledb store

Frontend integration:
- wefax.js plugin with live canvas rendering and gallery
- HTML sub-tab with canvas, gallery, toggle/clear controls
- SSE dispatch for wefax/wefax_progress events
- Decode history worker and restore support
- Toggle/clear API endpoints

19 unit tests covering resampler, FM discriminator, tone detection,
phasing, line slicing, image encoding, and decoder state machine.

https://claude.ai/code/session_019eyxgx3LuhcFZ7T5tr2Trm
Signed-off-by: Claude <noreply@anthropic.com>

docs/wefax_plan.md

@@ -1,7 +1,7 @@
 # WEFAX / Radiofax Decoder Implementation Plan
 
 > **Crate**: `trx-wefax` — `src/decoders/trx-wefax/`
-> **Status**: Draft — 2026-04-02
+> **Status**: Implemented (Phases 1–3b) — 2026-04-02
 
 ## 1. Overview
 
@@ -741,53 +741,53 @@ const HISTORY_GROUP_KEYS = [
 
 ## 8. Implementation Phases
 
-### Phase 1: Core DSP (MVP)
+### Phase 1: Core DSP (MVP) ✅
 
-1. **Resampler** — 48k→11025 polyphase resampler with tests.
-2. **FM discriminator** — Hilbert FIR + instantaneous freq, verify
+1. ✅ **Resampler** — 48k→11025 polyphase resampler with tests.
+2. ✅ **FM discriminator** — Hilbert FIR + instantaneous freq, verify
    against synthetic 1500–2300 Hz sweeps.
-3. **Tone detector** — Goertzel at 300/450/675 Hz with debounce.
-4. **Line slicer** — Fixed-config (manual LPM+IOC) line extraction.
-5. **Image buffer + PNG** — Greyscale line accumulation, `image` or
-   `png` crate for encoding.
+3. ✅ **Tone detector** — Goertzel at 300/450/675 Hz with debounce.
+4. ✅ **Line slicer** — Fixed-config (manual LPM+IOC) line extraction.
+5. ✅ **Image buffer + PNG** — Greyscale line accumulation, `png`
+   crate for encoding.
 
 Deliverable: decode a known WEFAX WAV recording at a single speed/IOC.
 
-### Phase 2: Automatic Detection
+### Phase 2: Automatic Detection ✅
 
-6. **State machine** — Full `Idle→StartDetected→Phasing→Receiving→Stopping`
+6. ✅ **State machine** — Full `Idle→StartDetected→Phasing→Receiving→Stopping`
    transitions driven by tone detector.
-7. **Phase alignment** — Cross-correlation phasing detector.
-8. **Auto IOC/LPM** — IOC from start tone frequency; LPM from phasing
+7. ✅ **Phase alignment** — Cross-correlation phasing detector.
+8. ✅ **Auto IOC/LPM** — IOC from start tone frequency; LPM from phasing
    line duration measurement.
 
 Deliverable: fully automatic reception of a single image without manual config.
 
-### Phase 3: Server Integration
+### Phase 3: Server Integration ✅
 
-9. **`trx-core` message types** — `WefaxMessage`, `WefaxProgress` in
+9. ✅ **`trx-core` message types** — `WefaxMessage`, `WefaxProgress` in
    `DecodedMessage`.
-10. **`trx-server` task** — `run_wefax_decoder()`, history, logging.
-11. **Protocol registry** — `DECODER_REGISTRY` entry for `"wefax"`.
+10. ✅ **`trx-server` task** — `run_wefax_decoder()`, history, logging.
+11. ✅ **Protocol registry** — `DECODER_REGISTRY` entry for `"wefax"`.
 
 Deliverable: backend wefax decoding with SSE event broadcast.
 
-### Phase 3b: Frontend Wiring
+### Phase 3b: Frontend Wiring ✅
 
-12. **Rust asset pipeline** — `status.rs` embed, `assets.rs` gzip
+12. ✅ **Rust asset pipeline** — `status.rs` embed, `assets.rs` gzip
     cache + route, `decoder.rs` toggle/clear endpoints, `api/mod.rs`
     registration (§7.5.1).
-13. **HTML scaffold** — sub-tab button, sub-tab panel with canvas +
+13. ✅ **HTML scaffold** — sub-tab button, sub-tab panel with canvas +
     gallery, overview entry, about row (§7.5.2).
-14. **Plugin loading** — add `/wefax.js` to `pluginScripts`
+14. ✅ **Plugin loading** — add `/wefax.js` to `pluginScripts`
     `'digital-modes'` array (§7.5.3).
-15. **SSE dispatch** — `wefax` / `wefax_progress` handlers in
+15. ✅ **SSE dispatch** — `wefax` / `wefax_progress` handlers in
     `app.js` decode event dispatcher (§7.5.4).
-16. **`wefax.js` plugin** — live canvas rendering, gallery
+16. ✅ **`wefax.js` plugin** — live canvas rendering, gallery
     thumbnails, history restore, toggle/clear wiring (§7.5.5).
 17. **Image serving** — `/images/{filename}` static route for
-    completed PNGs (§7.5.7).
-18. **History worker** — add `"wefax"` to `HISTORY_GROUP_KEYS`
+    completed PNGs (§7.5.7). *(deferred: images served from output_dir)*
+18. ✅ **History worker** — add `"wefax"` to `HISTORY_GROUP_KEYS`
     (§7.5.8).
 
 Deliverable: end-to-end live WEFAX decoding with in-browser image preview.