Add org-mode title extraction support (#50)

Refactor extractTitle to use extension-based extractors:
- .md: preserves original markdown logic (Notes skip behavior)
- .org: extracts from #+TITLE: property or first * heading

Extensions are lowercased for case-insensitive matching.
Easy to add more file types in the future.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/store.ts

@@ -891,17 +891,36 @@ export async function hashContent(content: string): Promise<string> {
   return hash.digest("hex");
 }
 
-export function extractTitle(content: string, filename: string): string {
-  const match = content.match(/^##?\s+(.+)$/m);
-  if (match) {
-    const title = (match[1] ?? "").trim();
-    if (title === "📝 Notes" || title === "Notes") {
-      const nextMatch = content.match(/^##\s+(.+)$/m);
-      if (nextMatch?.[1]) return nextMatch[1].trim();
+const titleExtractors: Record<string, (content: string) => string | null> = {
+  '.md': (content) => {
+    const match = content.match(/^##?\s+(.+)$/m);
+    if (match) {
+      const title = (match[1] ?? "").trim();
+      if (title === "📝 Notes" || title === "Notes") {
+        const nextMatch = content.match(/^##\s+(.+)$/m);
+        if (nextMatch?.[1]) return nextMatch[1].trim();
+      }
+      return title;
     }
-    return title;
+    return null;
+  },
+  '.org': (content) => {
+    const titleProp = content.match(/^#\+TITLE:\s*(.+)$/im);
+    if (titleProp?.[1]) return titleProp[1].trim();
+    const heading = content.match(/^\*+\s+(.+)$/m);
+    if (heading?.[1]) return heading[1].trim();
+    return null;
+  },
+};
+
+export function extractTitle(content: string, filename: string): string {
+  const ext = filename.slice(filename.lastIndexOf('.')).toLowerCase();
+  const extractor = titleExtractors[ext];
+  if (extractor) {
+    const title = extractor(content);
+    if (title) return title;
   }
-  return filename.replace(/\.md$/, "").split("/").pop() || filename;
+  return filename.replace(/\.[^.]+$/, "").split("/").pop() || filename;
 }
 
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