fix: bound Speech lifecycle terminal work

[douglasjarquin]

Closes #78

Summary

• Bound Speech startup, finalization, saved-audio retry, cancellation, interruption, and application shutdown with monotonic terminal budgets.
• Return control at deadlines without waiting inside a structured scope for noncooperative losing work.
• Keep CAF files and committed canonical raw segments recoverable while preventing volatile preview promotion after incomplete finalization.
• Fence late results, callbacks, retry commits, shutdown terminalization, metadata, HUD updates, insertion, and newer operations by operation identity and expected session state.
• Track owned loser tasks until actual completion and reap retained transcription resources only after the registry is empty.

Verification

• Exact head: 6c25d916843d5db28693a6968f86933e08403baa.
• Branch: codex/issue-78.
• swift build passed.
• swift build --product Oigo passed.
• The full local verify.yml command set passed, including the spike and issue 3 through issue 11 harnesses.
• The issue [V1 Phase 0 · P0] Bound Speech startup, finalization, cancellation, retry, and shutdown #78 harness passed all 12 scenarios, including the direct retry CAS regression, the late retry loser regression, the coordinator-level shutdown-versus-completed-retry regression, and 100 normal plus 100 adversarial lifecycle cycles.
• Issue [04/13 · MVP] Add on-device transcription and saved-audio retry #5 passed all 14 scenarios.
• LSP diagnostics are clean for all changed source and contract files.
• Five exact-SHA pre-PR review lanes passed: context, gate, code, QA, and security.

Native surface evidence

• Fresh launch artifact: /tmp/oigo-issue78-native-final-sha.rrdJoX/launch.png.
• The centered Welcome to Oigo Step 1 of 7 surface and native microphone prompt rendered coherently.
• The app log was empty and no microphone, TCC, Accessibility, or other permission was selected or changed.
• Microphone decision, later onboarding, live Speech capture, real finalization, saved-audio retry, interruption, shutdown interleavings, sleep or lock, relaunch, and long-run runtime remain INCONCLUSIVE because those host surfaces were unavailable.

Scope

• The unrelated open PR feat: persist microphone input selection #111 and the issue [V1 Phase 0 · P0] Support stereo and multi-channel inputs with one canonical mono stream #90 dependency gate were preserved.
• This PR is intentionally not merged.