docs: complete 0.13.6 docs sweep (architecture, api-design, disc-to-rip, README)

Follow-up to the rip-recovery + drive-access updates: aligns the
remaining docs with the v0.13.6 single-shot read model and the
three-layer recovery architecture.

- architecture.md: module map says single-shot read; new paragraph on
  layered recovery with postmortem pointer.
- api-design.md: EventKind enum example expanded; emission notes
  document that BytesRead now fires from DiscStream::fill_extents and
  Retry/SectorRecovered are no longer emitted in 0.13.6+.
- disc-to-rip.md: Step 10 of the pipeline diagram + module table
  reflect single-shot read.
- docs/README.md: added rip-recovery.md to the TOC.

docs/disc-to-rip.md

@@ -77,7 +77,9 @@ Insert disc
 10. Stream content (mux/disc.rs → DiscStream)
      │  Read sectors → decrypt → TS demux → PES frames
      │  Or: read sectors → decrypt → raw bytes (for ISO output)
-     │  Drive::read() handles error recovery (min speed → reset → retry)
+     │  Drive::read() is single-shot. DiscStream::fill_extents adapts the
+     │  batch size on failure (halve / probe-up). Bad-range retry is layer
+     │  1 above this — Disc::patch re-runs against the mapfile.
      │
      ▼
   PES frames → output stream (MKV, M2TS, network, etc.)
@@ -110,7 +112,7 @@ output.finish()?;
 
 | Module | Doc | Purpose |
 |--------|-----|---------|
-| drive/ | [drive-access.md](drive-access.md) | Open, identify, init, unlock, read (with recovery) |
+| drive/ | [drive-access.md](drive-access.md) | Open, identify, init, unlock, single-shot read |
 | scsi/ | [drive-access.md](drive-access.md) | Platform SCSI transport (Linux, macOS, Windows) |
 | udf.rs | [udf.md](udf.md) | UDF 2.50 filesystem |
 | mpls.rs | [mpls.md](mpls.md) | MPLS playlists + STN streams |