Fix Cowork editing and file responsiveness

[gitcommit90]

Outcome\n\nFixes the five Cowork regressions reported from the pasted brief.\n\n- Add shared speech-to-text controls and Option/Alt targeting for Cowork agent requests, Notes, and Docs.\n- Render Skipper's product avatar in Cowork.\n- Prevent stale Yjs histories from merging into a newly opened Cowork room and duplicating saved content.\n- Restore vertical scrolling in Cowork Notes Write mode.\n- Make Files selection immediate and decouple recursive folder-tree loading from directory clicks.\n\n## Verification\n\n- npm run typecheck\n- npm run build\n- npm test (117 native-world checks; 106 contracts, 2 environment-only skips)\n- Cowork browser regression proves saved content is present exactly once after leaving and reopening Cowork.\n- git diff --check