Integrate reviewed production runtime improvements

[hamzamerzic]

Summary

This brings the reviewed, still-useful production-only runtime work back upstream after #212:

• persist app-preview acknowledgement per exact build
• keep the mobile keyboard open for queue-only sends
• compile mini-app runtime bundles in production builds
• persist provider token usage against the exact chat run
• restore every opted-in running turn after a planned restart
• make drawer ownership and fast-close navigation deterministic
• project long historical activity into bounded, lazy detail ranges

Two review rounds

The first pass reviewed each feature against its owning persistence, navigation, capability, and runtime contracts. The second pass exercised the combined tree, migrations, live-data shapes, and failure boundaries.

Review fixes now included:

• cap every compact activity range at the activity-detail endpoint's 2,000-block contract, so every generated disclosure remains fetchable
• query tool-output sidecars only for IDs in the requested activity page
• bind each scheduled script path to the exact live app whose token and filesystem contract it receives
• fail closed when that scheduled-job identity is absent, instead of retaining a permanent compatibility bypass during updates
• preserve the authoritative chat handoff gate, so warm cached content cannot flash a deleted or stale destination
• keep the complete mobile modal boundary during a breakpoint transition until its history sentinel is consumed
• align browser fixtures with the compact transcript request so reconnect and persisted-question paths test the production contract

Deliberately excluded

• the production viewport zoom lock: it disables browser zoom and fails the current accessibility interface guidelines
• the cross-recompile quiet-CTA patch: its acknowledgement was not scoped to a turn, so an unopened final build from one turn could suppress the next turn's first preview
• superseded transcript-cache experiments; their useful performance behavior is replaced by bounded projection without weakening destination validation

Validation

• focused backend review suite: 282 passed
• scheduled-job follow-up suite: 12 passed
• frontend unit tests: 1,880 passed
• frontend hook tests: 47 passed
• production frontend build passed
• git diff --check and privacy/invariant scans passed
• read-only structural replay over 487 live chat shapes produced 4,697 valid lazy ranges with zero contract violations; recent-page payload was 83.7% smaller in aggregate (content was not printed or exported)

The final pushed head reruns the complete isolated backend, frontend, privacy, and browser suites.