docs: document 5A end-of-stream signal, chunk timing, fi==9 bug, ADC conversion

Adds §7.8.4 to protocol reference and corresponding CLAUDE.md sections:

- End-of-stream: device sends exactly 1 raw byte after last chunk; handled
  via TimeoutError + bytes_fed>0 check → graceful break to termination
- Chunk timing: ~1s per chunk, 35 chunks for a 9,306-sample event, safe
  timeout is 10s (not default 120s)
- fi==9 decoder bug: hardcoded skip drops ~133 sample-sets per event;
  noted as known issue pending fix
- ADC conversion: counts × (range/32767) → physical units (in/s for geo)

Changelog entries added for all four items (2026-04-06).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -157,6 +157,31 @@ record — 5A remains the sole source for those fields and they are set uncondit
 `stop_after_metadata=True` (default) stops the 5A loop as soon as `b"Project:"` appears,
 then sends the termination frame.
 
+### SUB 5A — end-of-stream signal (confirmed 2026-04-06)
+
+After streaming all waveform chunks, the device sends exactly **1 raw byte** in response to
+the next chunk request, then goes silent. This is the natural end-of-stream indicator — NOT
+a complete A5 frame. `S3FrameParser.bytes_fed` will be 1; no frame is assembled.
+
+Handling: on `TimeoutError`, if `bytes_fed > 0` AND frames were already collected, treat as
+graceful end-of-stream, break the loop, and proceed to the termination frame. If `bytes_fed
+== 0` with no prior frames, it is a genuine transport failure — re-raise.
+
+**Chunk recv timeout must be 10 s, not the default 120 s.** Chunks arrive within ~1 s each.
+Using 120 s causes a ~2-minute stall at every end-of-stream detection. The `_recv_one` call
+in the chunk loop passes `timeout=10.0` explicitly.
+
+**Typical chunk count (BE11529, 1024 sps):** A 9,306-sample event produces 35 chunks before
+end-of-stream. Chunks with uniform 1,036-byte data are all-zero ADC samples (post-event
+silence). Only the initial variable-size chunks contain actual signal.
+
+### SUB 5A — known decoder issue: fi==9 hardcoded skip (not yet fixed)
+
+`_decode_a5_waveform()` in `client.py` has `elif fi == 9: continue` — a leftover from the
+9-frame original blast capture where frame 9 was assumed to be a terminator. For current
+35-frame streams, fi==9 is live waveform data (~133 sample-sets dropped). Terminator
+detection is via `page_key == 0x0000`, not frame index. This skip should be removed.
+
 ### SUB 1E / 1F — event iteration null sentinel and token position (FIXED, do not re-introduce)
 
 **token_params bug (FIXED):** The token byte was at `params[6]` (wrong). Both 3-31-26 and