Why: track 2 of the fake-docx remediation — read-only preview fallback for stock text-masquerading docx artifacts; also ignore the Mimosa plugin's per-session .mimosa state dir that kept dirtying the tree and blocking precheck. Evidence: modules/ui 83367f7 (doc->binary dispatch + readable Office error), modules/frontend cd77340 (PK magic sniff + markdown fallback); make test-ui 49/49, make test-frontend 33/33, frontend tsc --noEmit clean. Impact: parent pins move to the two submodule branches; .gitignore gains .mimosa/; no code outside those modules. Refs: .task/feature-preview-sniff-fallback.md
ui
@ 83367f7c81