feat(ext): handcraft the whole ext from scratch

AI coding doesn't work for MV3 extensions.
Threading was an unfixable mess.
Removed everything and rebuilt by hand.

packages/extension/src/utils/index.ts

@@ -0,0 +1,28 @@
+/**
+ * Check if a URL can run content scripts.
+ */
+export function isContentScriptAllowed(url: string | undefined): boolean {
+	if (!url) return false
+
+	const restrictedPatterns = [
+		/^chrome:\/\//,
+		/^chrome-extension:\/\//,
+		/^about:/,
+		/^edge:\/\//,
+		/^brave:\/\//,
+		/^opera:\/\//,
+		/^vivaldi:\/\//,
+		/^file:\/\//,
+		/^view-source:/,
+		/^devtools:\/\//,
+	]
+
+	return !restrictedPatterns.some((pattern) => pattern.test(url))
+}
+
+/** LLM configuration */
+export interface LLMConfig {
+	apiKey: string
+	baseURL: string
+	model: string
+}