fix(dashboard): treat keyboard as closed on blur instead of waiting for vv settle

useMobileKeyboard now requires a focused input for keyboardOpen=true (both
the chrome-overlap and iOS-gap paths). The moment an input blurs, the hook
reports keyboardOpen=false instead of waiting hundreds of ms for iOS's
visualViewport dismissal animation to settle.

This makes App-level mobileKeyboardOpen flip false instantly on blur, so
MobileNavBar reappears and project-content regains nav-bar padding in the
same frame. The ChatView composer (and TodoModal/PlanningModeModal) snap
to their post-keyboard layout in one move instead of crawling down with
iOS's keyboard slide.

Replaces the per-component 450ms suppress hack in ChatView (also dropped
in this commit) which couldn't reach the parent layout's nav padding
state and produced "below tab bar then snap up" jitter.

Adds a regression test and updates four existing tests that assumed
"vv shrinks → keyboard up" without focus (focus is now required).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.changeset/fix-mobile-dashboard-pushed-up.md

@@ -6,4 +6,4 @@ Fix mobile keyboard regressions in the dashboard.
 
 - **Dashboard pushed up after closing a modal on mobile.** Adds a shared `useMobileScrollLock` hook that pins `body` with `position: fixed; top: -scrollY; width: 100%` while a fullscreen mobile overlay is open and restores scroll on cleanup — the same pattern Bootstrap, Headless UI, and Stripe Elements use to prevent iOS Safari from scrolling the document (and shifting `visualViewport.offsetTop`) when an input inside a `position: fixed` overlay is focused. Reference-counted so nested overlays don't release each other's locks. Wired into TodoModal, PlanningModeModal, TaskDetailModal, NewTaskModal, SettingsModal, MailboxModal, AddNodeModal, MissionInterviewModal, MilestoneSliceInterviewModal, SubtaskBreakdownModal, GitHubImportModal, AgentGenerationModal, AgentImportModal, ScriptsModal, ResearchTaskActionModal, and ChatView (replacing its inline body-overflow effect).
 - **Auto-reload prompt missed rebuilds.** Widens `computeBuildVersion` in `vite.config.ts` to hash the entire `app/` source tree (FN-3333 follow-up). The previous version only hashed `app/main.tsx` and `package.json`, so edits to any other component or stylesheet produced an identical build version and the version-check poll never noticed the rebuild.
-- **ChatView composer crawled down with iOS's keyboard-dismiss animation.** On blur, ChatView now suppresses keyboard-aware sizing for ~450ms so the composer snaps back to full height immediately instead of following iOS's slow keyboard slide-out (matches the existing QuickChatFAB behavior).
+- **ChatView composer crawled down with iOS's keyboard-dismiss animation.** `useMobileKeyboard` now requires a focused input for `keyboardOpen=true`. The moment any input blurs, `keyboardOpen` flips to `false` instead of waiting for iOS's slow visualViewport animation to settle (hundreds of ms). This propagates to App-level `mobileKeyboardOpen` so the MobileNavBar reappears and `project-content` regains its nav-bar padding immediately — chat-thread, modals, and any other consumer all snap to their post-keyboard layout in one frame.