Brings in the plugin-side file-icon feature (issue #611): the public
`registerFileIcon` API plus the resolver chain the tree, the editor tab and
the external-plugin surface all read.
Conflicts (three, all comment/list unions — resolved by union, verified green):
- src/client/service.ts: main's "v0.19.0 REMOVED 'floatWindows'" note stays
(the capability is gone and must not come back); the feature list gains
'fileIcons'.
- src/client/Sidebar.tsx: one comment above `tabIconOf`; both sides' wording
is kept (the editor-with-path special case and the descriptor fallback).
- docs/external-plugin-guide.md: the `features` list comment keeps main's
"additive only, the one exception being floatWindows" wording plus the new
'fileIcons' entry.
Notes on what this merge does NOT bring in: #594 (feat/file-icon-theme) is
stacked on this branch and lands next, but its colored-theme implementation
(563-entry react-icons dataset in a 255 kB lazy chunk plus a `fileIconTheme`
switch) is being replaced — DSH 0.1.5-rc.2 exports the official
`FileTypeIcon`/`CodeFileIcon` artwork from ui-primitives, so the plugin does
not need to ship its own color dataset.
Gates on the merge result: pnpm typecheck clean, pnpm test 127 files /
1331 passed / 9 skipped.
Menghuan1918
1d05e39be2