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/bun/fs/registry.ts

@@ -0,0 +1,42 @@
+import { LocalProvider } from "./local";
+import type { FileSystemProvider } from "./provider";
+
+export const LOCAL_SESSION_ID = "local";
+
+/**
+ * Maps sessionId -> provider. "local" is always available; each SFTP connect
+ * adds a new session (one SSH connection per panel-connect, no refcounting).
+ */
+export class SessionRegistry {
+	private sessions = new Map<string, FileSystemProvider>([
+		[LOCAL_SESSION_ID, new LocalProvider()],
+	]);
+	private counter = 0;
+
+	get(sessionId: string): FileSystemProvider {
+		const provider = this.sessions.get(sessionId);
+		if (!provider) throw new Error(`Session "${sessionId}" is not connected`);
+		return provider;
+	}
+
+	add(provider: FileSystemProvider): string {
+		const id = `sftp-${++this.counter}`;
+		this.sessions.set(id, provider);
+		return id;
+	}
+
+	async remove(sessionId: string): Promise<void> {
+		if (sessionId === LOCAL_SESSION_ID)
+			throw new Error("The local session cannot be disconnected");
+		const provider = this.sessions.get(sessionId);
+		if (!provider) return;
+		this.sessions.delete(sessionId);
+		await provider.dispose();
+	}
+
+	/** Remove without dispose — for sessions that died on their own. */
+	drop(sessionId: string): void {
+		if (sessionId === LOCAL_SESSION_ID) return;
+		this.sessions.delete(sessionId);
+	}
+}