fix: route all Home/meeting own-file access through one resilient resolver (stop the reveal/delete whack-a-mole)

[r3dbars]

Why

The Home/meeting three-dots menu has been a string of dead controls patched one PR at a time — #1126 (delete confirmation), #1131 (delete-failure alert), #1134 (reveal/delete stale paths). They share one root cause: every Home/meeting control holds the file URL captured when the dashboard was last scanned, but background work moves those files afterward — the post-save restyle renames the transcript and its audio/<stem>_audio/ bundle, a preview rename moves the transcript + summary sidecar, and retained audio is recompressed WAV→M4A. A raw activateFileViewerSelecting / NSWorkspace.open / NSSound(contentsOf:) on a stale path silently no-ops — the "Show … in Finder does nothing / works on one machine but not another" reports.

This generalizes #1134's HomeArtifactRevealResolver into a single resolver every own-file access routes through, so a drifted path surfaces an error instead of a dead click — and a re-introduced dead control fails CI.

Note: based on origin/main (pre-#1134, which is still open). #1134's reveal/delete fixes are subsumed here; if #1134 lands first this will need a trivial rebase in TranscriptedSettingsView.swift.

What

OwnFileResolver (Sources/UI/Shared/OwnFileResolver.swift) — two intent-specific modes:

• resolveForReveal: existing → stem-rematch (WAV→M4A) → enclosing folder → .unavailable. Revealing a folder beats a dead click.
• resolveExistingFile / resolveExistingFiles: existing → stem-rematch only, no directory fallback (you can't open/read/play a folder). Returns nil so the caller surfaces an error.

Every Home/meeting control routed through it, each surfacing a failure alert instead of a silent no-op / NSSound.beep:

• reveal in Finder: meeting transcript, meeting audio, failed-meeting audio, dictation
• open: meeting preview, summary notice, enhanced transcript, current-activity card, dictation row + menu
• copy-for-agent & re-transcribe: resolve the source first, error if missing
• retained-audio playback: resolve each source so recompressed audio still plays
• meeting-preview read: follow a drifted transcript instead of erroring

Delete deliberately does NOT use the lenient resolver — stem/folder fallback could remove the wrong file. Instead it detects a no-op delete on a stale path and surfaces it (port of #1134) so the row never silently reappears.

Tests (a dead control / broken own-file path fails CI)

• OwnFileResolverTests — temp-dir behavioral coverage of both modes: direct hit, WAV→M4A stem rematch, enclosing-folder fallback, no-dir-fallback for open, multi-file drop-missing, dedup, unavailable.
• UIAutomationSurfaceContractTests — assert every reveal/open/delete/playback site routes through OwnFileResolver and no raw stale-path NSWorkspace call remains.
• RepoCommandContractTests — strengthened the delete gate to require the stale-path no-op detection.

Fast suite: 5441 passed, 0 failed (bash run-tests.sh).

Proof still needed

• Full app build (bash build.sh) requires prebuilt SPM deps not present in this fresh worktree (build-deps.sh); compiled in CI. The fast suite compiles OwnFileResolver and all contract gates pass.
• Manual UI smoke: rename/restyle a meeting, then exercise Show-in-Finder / Open / Re-transcribe / Delete from the row menu and confirm each either follows the file or shows an error alert (never a dead click).

Scope

Confined to Home/meeting interaction + the app's own-file resolution + tests. No audio-capture, pipeline, or dependency changes. No existing test weakened (the one delete-block assertion was updated to match the refactor and strengthened with the no-op gate).