docs(cr-2026-04-22): add release-blocker issue tracker at docs/issues/

Captures the 12 items from docs/code-review-2026-04-22.md that
must land before v0.1 ships. One markdown file per issue with:
severity, path:line, problem description, acceptance criteria,
fix scope, and dependency graph.

Split by severity:
- 3 CRITICAL: live-session race, migration atomicity, transcript-
  profile FK
- 9 MAJOR: monolith refactor, channel-fatality, capture worker
  join, runtime capabilities, macOS App Nap, decoder error prop,
  LLM prompt preflight, keystore thread-safety, hotkey device
  filter

README.md indexes them with a fix-order dependency graph and a
fish-shell script for bulk-converting to GitHub issues once `gh`
CLI is installed and authed. Deferred step by user decision —
markdown tracker is authoritative until then.

docs/issues/native-capture-worker-join.md

@@ -0,0 +1,24 @@
+# RB-06 MAJOR: native capture worker is detached, can outlive stop/start
+
+**Severity:** MAJOR
+**Path:** `src-tauri/src/commands/audio.rs:46-228`
+**Source:** [2026-04-22 code review](../code-review-2026-04-22.md)
+**Labels:** release-blocker, major, concurrency, audio
+
+## Problem
+
+`start_native_capture` and `stop_native_capture` coordinate through a channel but never retain the spawned worker handle. A previous capture can still be flushing / appending after `stop_native_capture` clears `all_samples` and before a new `start_native_capture` takes it — output can be truncated or contaminated with cross-session samples.
+
+## Acceptance
+
+- Store the worker's `JoinHandle` in the native capture state.
+- `stop_native_capture` awaits the handle before returning — start/stop/start is fully serialised.
+- Regression test: rapid start → stop → start sequence produces two distinct samples vectors with no cross-session leakage.
+
+## Fix scope
+
+Medium. Requires adding `JoinHandle` storage and making the stop path `await` cleanly — probably needs a small refactor of the native capture state struct.
+
+## Dependencies
+
+- Independent of other items, though the fix pattern (retain handles, join on stop) mirrors what RB-04 will do for the live-session worker.