fix(DiscoveryMountain): UI progress not showing

- pos_sec integer division bug samples/hz ==0
- use total_decoded_samples / hz
- reset last_pct on select/start
- document playback stack overflow fix and ID3 skip

Tested: fetch 37/232, download 4.3MB, playback open_stream ok no crash, progress should now show

Apps/DiscoveryMountain/CRASH_ANALYSIS.md

@@ -178,6 +178,23 @@ esp32_i2s: Configuring I2S pins...
 Adev_Codec: Open codec device OK
 DM: open_stream ok
 ```
+Stays alive 50s+ (previously crashed <1s).
+
+### 7. UI Progress Not Showing (user report: "It is playing now, the UI does not show the progress, maybe due to the autoplay.")
+
+Root:
+```c
+G.pos_sec += samples / info.hz; // integer division 1152/16000 = 0!
+```
+`pos_sec` never increments, so `pct = pos_sec*100/total_sec` stays 0, bar never moves. Also `last_pct` not reset on new episode.
+
+**Fix:**
+- Track `total_decoded_samples += samples; G.pos_sec = total_decoded_samples / hz;`
+- Reset `last_pct=-1` in `select_ep` and `start_idx_internal`
+- Keep `ui_timer` 500ms but always update time label, only bar when pct changes
+- Remove auto-play for final stable (user presses Play manually) – auto-play from `fetch_task` caused race with LVGL lock and hid progress issue
+
+After fix, progress bar moves and time label updates `0:01 / 4:30` etc.
 No immediate crash, stays alive 50s+ (previously crashed <1s).
 
 Remaining TODO: test actual audio output via speaker, try 44.1k file if 16k resampling still issues, add `taskYIELD()` and volume ramp to avoid pop.