P1: typed RPC bridge + FileSystemProvider + dual-panel local browsing

- shared/types + shared/rpc: full wire contract (Result envelope, no exceptions cross the bridge)
- FileSystemProvider interface, LocalProvider, SessionRegistry with built-in 'local'
- walk.ts: provider-generic recursive walk + removeRecursive
- rpc-handlers wired into BrowserWindow; 10min request timeout for slow SFTP ops
- Angular: RpcService (Electroview bridge + plain-browser guard), PanelsService with
  signals-based PanelState (sort/cursor/selection), FilePanel component with
  keyboard nav (arrows/Space/Enter/Backspace/Tab), path bar, toasts
- verified: both panels listDir home over the bridge in the running app

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/shared/rpc.ts

@@ -0,0 +1,80 @@
+import type {
+	ConnFolder,
+	ConnectionConfig,
+	ConnectionsFile,
+	EntryType,
+	FileEntry,
+	Result,
+	SavedConnection,
+	TransferSnapshot,
+} from "./types";
+
+// Structurally equivalent to electrobun's ElectrobunRPCSchema, written in
+// resolved form so this file stays importable from the Angular bundle without
+// pulling in bun-only type modules.
+//
+// bun.requests    = calls the webview makes, handled in src/bun/rpc-handlers.ts
+// webview.messages = push events from bun, handled in ui rpc.service.ts
+export type AppRPC = {
+	bun: {
+		requests: {
+			// sessions
+			connect: {
+				params: { config: ConnectionConfig };
+				response: Result<{ sessionId: string; homeDir: string }>;
+			};
+			disconnect: { params: { sessionId: string }; response: Result };
+			// filesystem (uniform across "local" and sftp sessions)
+			listDir: {
+				params: { sessionId: string; path: string | null }; // null -> home dir
+				response: Result<{ path: string; entries: FileEntry[] }>;
+			};
+			mkdir: { params: { sessionId: string; path: string }; response: Result };
+			createFile: { params: { sessionId: string; path: string }; response: Result };
+			rename: {
+				params: { sessionId: string; oldPath: string; newPath: string };
+				response: Result;
+			};
+			deleteEntries: {
+				params: { sessionId: string; entries: { path: string; type: EntryType }[] };
+				response: Result;
+			};
+			chmod: {
+				params: { sessionId: string; paths: string[]; mode: number };
+				response: Result;
+			};
+			// transfers
+			enqueueTransfers: {
+				params: {
+					srcSessionId: string;
+					items: { path: string; type: EntryType }[];
+					dstSessionId: string;
+					dstDir: string;
+				};
+				response: Result<{ jobIds: string[] }>;
+			};
+			cancelTransfer: { params: { jobId: string }; response: Result };
+			dismissTransfer: { params: { jobId: string }; response: Result };
+			// connection store
+			getConnections: {
+				params: Record<string, never>;
+				response: Result<{ store: ConnectionsFile }>;
+			};
+			upsertConnection: {
+				params: { connection: SavedConnection };
+				response: Result<{ id: string }>;
+			};
+			deleteConnection: { params: { id: string }; response: Result };
+			upsertFolder: { params: { folder: ConnFolder }; response: Result<{ id: string }> };
+			deleteFolder: { params: { id: string }; response: Result };
+		};
+		messages: Record<never, never>;
+	};
+	webview: {
+		requests: Record<never, never>;
+		messages: {
+			transferUpdate: TransferSnapshot;
+			sessionClosed: { sessionId: string; reason: string };
+		};
+	};
+};