New files:
- project-state.types.ts: all per-project state interfaces
- project-state.svelte.ts: unified per-project state with version counter
- app-state.svelte.ts: root facade re-exporting all stores as appState.*
Rewired components (no more local $state):
- ProjectCard: reads via appState.agent.* and appState.project.tab.*
- TerminalTabs: state in appState.project.terminals.*
- FileBrowser: state in appState.project.files.*
- CommsTab: state in appState.project.comms.*
- TaskBoardTab: state in appState.project.tasks.*
All follow Rule 57 (no $derived with new objects) and Rule 58
(state tree architecture, components are pure renderers).
