Add trust features: history, trash, export, and collection sharing

Implement Notion-like upgrade phase 4: append-only page revisions with restore-as-a-new-version; recoverable bookmark/page/collection deletions whose restores never resurrect public flags or shares; owner-scoped JSON export; and explicit, revocable read-only collection sharing with owner-only mutations and no transitive third-party bookmark leaks. Add migration 009, API/docs, integration coverage, and page/collections/trash UI.

internal/http/server.go

@@ -89,8 +89,17 @@ func NewServer(cfg *config.Config, database *db.DB) *http.Server {
 	mux.HandleFunc("PATCH /api/pages/{id}", authed(handlers.HandlePagesUpdate))
 	mux.HandleFunc("DELETE /api/pages/{id}", authed(handlers.HandlePagesDelete))
 	mux.HandleFunc("GET /api/pages/{id}/backlinks", authed(handlers.HandlePagesBacklinks))
+	mux.HandleFunc("GET /api/pages/{id}/revisions", authed(handlers.HandlePageRevisionsList))
+	mux.HandleFunc("GET /api/pages/{id}/revisions/{revisionId}", authed(handlers.HandlePageRevisionsGet))
+	mux.HandleFunc("POST /api/pages/{id}/revisions/{revisionId}/restore", authed(handlers.HandlePageRevisionsRestore))
 	mux.HandleFunc("GET /api/pages/{id}/markdown", authed(handlers.HandlePagesMarkdown))
 
+	// Trust phase: recoverable deletions and structured export.
+	mux.HandleFunc("GET /api/trash", authed(handlers.HandleTrashList))
+	mux.HandleFunc("POST /api/trash/{id}/restore", authed(handlers.HandleTrashRestore))
+	mux.HandleFunc("DELETE /api/trash/{id}", authed(handlers.HandleTrashPurge))
+	mux.HandleFunc("GET /api/export", authed(handlers.HandleExport))
+
 	// 4.7 Signals
 	mux.HandleFunc("GET /api/bookmarks/{id}/signals", authed(handlers.HandleSignalsList))
 	mux.HandleFunc("POST /api/bookmarks/{id}/signals", authed(handlers.HandleSignalsCreate))
@@ -118,6 +127,8 @@ func NewServer(cfg *config.Config, database *db.DB) *http.Server {
 	mux.HandleFunc("GET /api/collections/{id}", authed(handlers.HandleCollectionsGet))
 	mux.HandleFunc("PATCH /api/collections/{id}", authed(handlers.HandleCollectionsUpdate))
 	mux.HandleFunc("DELETE /api/collections/{id}", authed(handlers.HandleCollectionsDelete))
+	mux.HandleFunc("POST /api/collections/{id}/share", authed(handlers.HandleCollectionShare))
+	mux.HandleFunc("DELETE /api/collections/{id}/share/{userId}", authed(handlers.HandleCollectionUnshare))
 	mux.HandleFunc("POST /api/collections/{id}/properties", authed(handlers.HandleCollectionPropertiesCreate))
 	mux.HandleFunc("PATCH /api/collections/{id}/properties/{propertyId}", authed(handlers.HandleCollectionPropertiesUpdate))
 	mux.HandleFunc("DELETE /api/collections/{id}/properties/{propertyId}", authed(handlers.HandleCollectionPropertiesDelete))