feat(web): searchable session picker on Android share target

[heavygee]

Summary

Adds a searchable session picker to the Android Web Share Target (/share) flow.

• Reuses sidebar session search (SessionListSearch, sessionMatchesQuery) so inactive sessions are findable by title, machine label, or path
• Empty query: capped list of recent active sessions (same limit as sidebar preview)
• Non-empty query: searches all sessions
• Unit tests for filter/cap logic (sharePickerSessions.test.ts)

Builds on merged share-target work (#933, #932).

Test plan

• bun typecheck
• cd web && bun run test (includes sharePickerSessions.test.ts)
• Peer-stack Playwright (e2e/peer/980-share-target-session-search.spec.ts on fork main)
• Operator dogfood on driver soup :3006 — share sheet → /share → search inactive session

Issues

Fixes #980

[heavygee]

Peer-stack Playwright + operator dogfood on driver soup (:3006) — share sheet → /share → search finds inactive sessions. Screenshot: localdocs/playwright-runs/share-target-session-search.png on fork branch (not committed per upstream PR discipline).

[github-actions]

Findings

• [Major] Inactive share targets can drop the pending transfer — search mode now returns inactive sessions, but selecting one still arms sessionStorage and navigates straight to /sessions/:id. ShareSeedConsumer consumes and removes that transfer id on the inactive session mount, then waits for sessionActive; if the operator reopens/resumes into a new session id, the keyed chat remount has no pending transfer left, so the shared text/files are never attached. Evidence: web/src/lib/sharePickerSessions.ts:26, related consumer behavior in web/src/components/SessionChat.tsx:205 and web/src/components/SessionChat.tsx:214.
  Suggested fix:

  useEffect(() => {
      if (!props.sessionActive) return
      if (consumedRef.current) return
      const transferId = consumeSharePendingTransfer()
      if (!transferId) return
      consumedRef.current = true
  
      void seedShareTransfer(transferId)
  }, [props.sessionActive, props.sessionId, assistantApi])

Summary

• Review mode: initial
• The searchable picker is mostly localized, but the newly reachable inactive-session path can lose the Web Share Target payload before the target session is active.

Testing

• Not run (automation): bun is not available on this runner (bun: command not found).

[github-actions]

[MAJOR] This branch now makes inactive sessions selectable from the share picker, but the downstream share seeding path only works after SessionChat is active. Today ShareSeedConsumer consumes and removes the pending transfer id on first mount, then returns while props.sessionActive is false; if the user reopens/resumes into a new session id, the keyed chat remount no longer has the transfer in sessionStorage, so the shared text/files are lost.

Suggested fix:

useEffect(() => {
    if (!props.sessionActive) return
    if (consumedRef.current) return
    const transferId = consumeSharePendingTransfer()
    if (!transferId) return
    consumedRef.current = true

    void seedShareTransfer(transferId)
}, [props.sessionActive, props.sessionId, assistantApi])