Switch exec to fire-and-forget spawn, drop awaits

spawnSync was blocking the event loop until the subprocess exited, so
opening a browser would freeze the server until it closed. Replace with
spawn + unref (detached, stdio ignored) and remove the now-pointless
awaits and async keywords from action handlers.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/actions.mjs

@@ -9,7 +9,7 @@ export const actions = {
 		description: "List all available actions and their definitions",
 		params: [],
 		policy: "auto-accept",
-		handler: async () => {
+		handler: () => {
 			return Object.entries(actions).map(([name, def]) => ({
 				action: name,
 				description: def.description,
@@ -23,9 +23,9 @@ export const actions = {
 		description: "Open a file in the editor",
 		params: [{ name: "filename", required: true, type: "path" }],
 		policy: "auto-accept",
-		handler: async ({ filename }) => {
+		handler: ({ filename }) => {
 			const resolved = resolve_path(filename);
-			await exec('subl3', [resolved]);
+			exec('subl3', [resolved]);
 			return { opened: resolved };
 		},
 	},
@@ -35,9 +35,9 @@ export const actions = {
 		description: "Open a directory in the file manager",
 		params: [{ name: "path", required: true, type: "path" }],
 		policy: 'queue',
-		handler: async ({ path }) => {
+		handler: ({ path }) => {
 			const resolved = resolve_path(path);
-			// await exec( ... );
+			// exec( ... );
 			return { opened: resolved };
 		},
 	},
@@ -47,12 +47,12 @@ export const actions = {
 		description: "Open a URL in the web browser",
 		params: [{ name: "url", required: true, type: "string" }],
 		policy: "queue",
-		handler: async ({ url }) => {
+		handler: ({ url }) => {
 			const parsed = new URL(url);
 			if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
 				throw new Error(`Disallowed protocol: ${parsed.protocol}`);
 			}
-			await exec('xdg-open', [parsed.href]);
+			exec('xdg-open', [parsed.href]);
 			return { opened: parsed.href };
 		},
 	},
@@ -61,9 +61,9 @@ export const actions = {
 		description: "Open a terminal in a given directory",
 		params: [{ name: "path", required: false, type: "path" }],
 		policy: 'queue',
-		handler: async ({ path }) => {
+		handler: ({ path }) => {
 			const resolved = resolve_path(path ?? 'workspace');
-			await exec('konsole', ['--workdir', resolved, '-e', 'bash']);
+			exec('konsole', ['--workdir', resolved, '-e', 'bash']);
 			return { opened: resolved };
 		},
 	},