refactor!: remove redundant compatibility layers

Use native browser and Tauri behavior instead of custom selector, dialog, and window-state implementations. Remove obsolete bridge, relay, asset, and dependency paths to keep the supported surface small.

BREAKING CHANGE: The Noctalia relay no longer accepts --agent, and the Tauri host no longer exposes the legacy load_agent command.

src/bridge/agent-registry.js

@@ -1799,7 +1799,7 @@ export function createAgentRegistry({
 		async stop() {
 			stopping = true;
 			while (pendingOpenOperations.size > 0)
-				await Promise.allSettled([...pendingOpenOperations]);
+				await Promise.allSettled(pendingOpenOperations);
 			const runtimes = [...runtimesByRuntimeId.values()];
 			await Promise.all(runtimes.map((runtime) => runtime.operationQueue));
 			await Promise.all(
@@ -1815,5 +1815,4 @@ export function createAgentRegistry({
 	};
 }
 
-export const sessionDirectoryMode = SESSION_DIRECTORY_MODE;
 export const sessionDirectoryPath = sessionDirectoryFor;