Remove non-vault providers and cascade dead code
Textile is now vault-only. Remove the standalone document/filesystem
providers and everything they kept alive:
Providers:
- documents: automerge, habitat, subtext
- filesystem: automerge, habitat, subtext, remoteSync (stub)
- App.tsx: drop staticProviders + isSubtextEnabled; the sidebar lists
only vault providers.
Yjs stack (only the removed providers produced 'yjs' bindings):
- editors/yjs/* + the registry 'yjs' entry; EditorKind is now 'automerge'.
- habitat/docSession.ts (+ test) and habitat/connectionProvider.ts;
libp2pNode now sources HabitatLibp2pNode from automergeConnectionProvider.
- habitatDoc.ts trimmed to the CRDT-agnostic URI helpers (parseDocUri,
editRkeyFor) the vault stack still uses.
- automergeDocSession: dropped the now-subscriber-less title-emit machinery.
Subtext subsystem (fully):
- src/subtext/*, the main-process SubtextTCPClient + IPC handlers, the
preload/vite-env bridge, and the Settings → Subtext pane + icon.
Dependencies orphaned by the above:
- yjs, y-protocols, @tiptap/* (the old TipTap/Yjs editor), protobufjs(+cli)
and the dead proto:gen script, it-byte-stream. Kept lib0 (used by the
automerge connection provider).
Net ~-9.4k lines of source. Lint/tsc/tests clean (56 passing).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>