fix(app): improve touch controls and standalone PWA relaunch - #46391

Summary

• Keep transcript copy controls, agent/model/time metadata, and shell/code/tool actions visible on non-hover devices while preserving desktop hover and keyboard-focus behavior.
• Keep touch input placeholders compact at 13px while actual entered text remains 16px to avoid iOS focus zoom.
• Detect standalone PWA mode and restore the last allowed route at root startup, then persist router location; retain the existing URL router rather than introducing a separate memory router.

Related PRs

Independent against v2. The mobile UI stack is #46388 (shell/Home/settings), #46389 (session panels), and #46390 (diff review). This PR can merge separately; its shared review CSS changes are limited to non-hover Open file visibility, separate from #46390's summaries and header layout.

Sessions

• ses_fa8ce9ae1ffeJaH6I8O4Ut1d67: touch transcript controls and metadata.
• ses_fa8f428cfffe2PwaFX2PhjaYy0: compact iOS placeholders.
• ses_fa8c9b9c6ffeULe3oLIORr07X2: standalone PWA route restoration.
• Commits retain these associations as Session-Id trailers.

Before / After

Touch controls, compact mobile placeholders, and standalone PWA route restoration. Before/after captures use real production components with deterministic fixture data at 390x844, light mode, English, UTC, and touch input.

Surface	Before	After
Message copy actions and agent/model/timestamp metadata without hover
Completed shell command copy without hover
Code Mode execution copy without hover
Fenced Markdown code copy without hover
Webfetch external-link affordance without hover
Expanded patch failure copy without hover
Compact mobile input placeholders while input font stays 16px
Standalone relaunch: Home before, restored Session after
Delegated task Session navigation affordance without hover
Shared review Open File control without hover

• All ten pairs were visually inspected. No live personal data or credentials are included.
• Task navigation and shared review screenshots use a temporary fixture rendering the real ToolDisplay and SessionReview with existing providers and local no-op callbacks. The temporary story was removed from the worktree after capture; no production component changes or extra commits were made.
• The legacy session-turn diff toggle has no active TSX consumer, so there is no user-visible surface to capture.
• PWA standalone mode is emulated using navigator.standalone; service workers are blocked. This comparison verifies route restoration, not an actual installed-device lifecycle.

Validation

• CI Linux/Windows E2E and typecheck passed. Linux unit CI failed in untouched CLI ACP permission-behavior timeout (2 seconds); Linux rerun failed with the same untouched CLI timeout; Windows rerun is pending. UI tests passed locally.
• All four PR groups merge cleanly in an isolated integration worktree; the combined production build passes all eight mobile browser regressions and app typechecking.
• App and session-ui package typechecks, production app build, formatting, and diff checks pass.
• Five PWA unit tests; all 74 app browser tests; all 166 session-ui unit tests pass.
• Five component regressions pass, covering mobile non-hover metadata/actions, shell/error controls, and desktop hover/keyboard focus.
• Production navigation benchmark passes before and after: stable content 134.8ms on clean v2 and 139.8ms on this head; stable tab 47.4ms and 46.2ms. Single machine-local samples, not statistical performance conclusions.
• PWA capture uses emulated standalone detection, not an actual installed-device lifecycle; service workers are blocked to isolate route restoration.
• Actual iOS Safari focus zoom still needs device validation. No production behavior was added solely for screenshots.
• Original dirty user worktree/staging and existing app/server processes remain untouched. This does not duplicate the already-merged channel favicon/PWA icon PR.