feat: add reviewable talking-head cleanup

[appergb]

Summary

• add a dynamically discovered remove_filler_words workflow with strict arguments and word-level project-frame transcript matching
• return stable, reviewable filler-word cuts and apply only accepted cuts through per-track ripple-delete commands
• preserve linked audio/video alignment, rejected filler phrases, durable undo, and correct global lower-track ripple behavior
• close the planned SRT/VTT, editor TitleBar, interchange-export, schema-safe UI persistence, complete application-menu, recent-project-card, Home secondary-control, Home open-project, and Home new-project slices with exact owning tests and packaged macOS acceptance
• version editor layout, panel, and keyframe preferences under isolated opentake.ui.v1.* keys with strict legacy migration, malformed-data recovery, and unavailable-storage safety while keeping project state out of browser persistence
• install the full native App/File/Edit/View/Help command matrix with shared actions, live enabled/checked state, runtime locale updates, Settings deep links, and atomic project Save As
• make Home project lifecycle actions globally single-flight: all New, Open, and recent-project entries share a native pending gate and reject overlapping transitions
• move project opening off the async executor, time out cloud-backed filesystem stalls after 15 seconds, preserve the live project on failure, and surface localized recovery errors
• make first-save project creation atomic: persist and reopen a separate fresh core before committing it to the live session, so creation failure cannot discard the active project
• integrate feat: finalize generation provider workflows #234 atomic generated-media publication so Windows can replace a complete bundle without retained live-target handles
• preserve generated media, manifest, and generation log as one journaled publication transaction, with exact byte-count validation and rollback tests
• explicitly release a successful bundle publication lock before returning so an immediate generation-state save can begin without a transient WouldBlock
• implement and package-verify the Default, Media, and Vertical five-panel layouts with exact ratios, collapse/maximize behavior, localized semantic regions, keyboard-resizable splitters, and visible focus transfer

Verification

• cargo test --workspace — full-workspace pass, including 370 Tauri tests and the project lifecycle, generation retry, and publication-lock regressions
• generation retry and 32-publication lock-handoff regressions — 25 consecutive paired passes
• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo clippy -p opentake-tauri --no-default-features --all-targets -- -D warnings
• pnpm -C web test -- --run — 75 files / 749 tests passed
• pnpm -C web build
• ./web/node_modules/.bin/tauri build --debug — app and DMG bundles produced
• default and --no-default-features Tauri checks passed
• feat: finalize generation provider workflows #234 CI — Rust, Web, all safe-filesystem jobs, Windows security/cancel tests, and Windows full product/bundle passed
• real packaged macOS SRT/VTT, TitleBar, XMEML/FCPXML/OTIO/EDL, five-panel layouts, schema-safe persistence, complete App/File/Edit/View/Help menu, recent-project-card, Home secondary-control, Home open-project, and Home new-project runs passed
• persistence validation covered restart restoration, project reopening, corrupted/legacy keys, per-key write failure, default restoration, and exclusion of playhead/selection/project state
• native menu validation covered Home/editor disabled rules, selection and clipboard transitions, atomic Save As, Save, Import cancel, Export cancel, fullscreen, focus restoration, and Chinese ↔ English live label synchronization
• FileProvider regression: a cloud-backed open(2) stall kept the main window responsive, recovered with a visible timeout, and left a valid TalkingHeadQA project openable in the same process
• project-creation regression: all three Home entry points produced valid reusable bundles; cancel and invalid-path failure recovered without replacing the active project

Runtime evidence:

• docs/audit/2026-07-14/runtime-artifacts/automated/talking-head-cleanup-2026-07-29.md
• docs/audit/2026-07-14/runtime-artifacts/automated/subtitle-export-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/titlebar-controls-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/interchange-export-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/five-panel-layout-real-device-2026-07-31.md
• docs/audit/2026-07-14/runtime-artifacts/automated/schema-safe-persistence-real-device-2026-07-31.md
• docs/audit/2026-07-14/runtime-artifacts/automated/view-menu-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/view-menu-contract-real-device-2026-07-31.md
• docs/audit/2026-07-14/runtime-artifacts/automated/recent-project-card-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/home-secondary-controls-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/home-open-project-real-device-2026-07-30.md
• docs/audit/2026-07-14/runtime-artifacts/automated/home-new-project-real-device-2026-07-31.md
• docs/audit/2026-07-14/runtime-artifacts/automated/generation-finalization-2026-07-29.md

Stacking

This PR is intentionally based on #234 (agent/generation-finalization). The completed slices above are verified, but the remaining project audit and Beta release stay open until the outstanding plan items are implemented and exercised in order.