Fix transcript history session linkage

[pranc1ngpegasus]

Summary

• Allocate the database session before audio starts and attach its session ID to every runner update.
• Ignore stale lifecycle/transcription updates and prevent history navigation from replacing an active or not-yet-persisted transcript.
• Persist the final transcript atomically and idempotently, with session-ID validation and retryable failure handling.
• Keep recorded WAV paths aligned with stored paths and reserve recording directories exclusively.
• Distinguish unstarted failures from partial recordings so empty failed sessions are deleted while recoverable output is preserved.

Root cause

The live recording and history views shared the same in-memory segment buffer. Navigating to an older history item while recording or stopping could replace that buffer; the eventual stop handler then persisted the visible historical segments under the active session ID. Lifecycle updates also lacked a stable session identity, so delayed updates could mutate a newer session.

Impact

Transcripts now remain bound to the session that produced them across navigation, delayed worker events, start/stop failures, persistence retries, and application shutdown. Existing already-corrupted rows are not rewritten because their intended association cannot be inferred safely.

Integration

Rebased onto the latest origin/main (fae9982), retaining the input-device-change handling from #77 and incorporating the recording-path linkage intent from #78 into the preallocated-session flow.

Validation

• cargo test -p wisp-desktop --features gpui/runtime_shaders (35 passed)
• cargo test --workspace --exclude wisp-desktop --all-targets
• cargo clippy -p wisp-storage --all-targets -- -D warnings
• swift build --package-path native/WispAudioKit --jobs 4
• cargo fmt --all -- --check
• git diff --check