Add PDF file attachments to components

- Upload PDFs, rename them (conflict-checked), delete them
- Link/unlink files per component (many components can share a file)
- File picker dialog: browse existing files, rename inline, upload new
- Component detail shows linked files as clickable links
- Files stored in data/pdfs/, served at /pdf/:filename
- KV prefix: pdf:

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

lib/storage.mjs

@@ -147,6 +147,28 @@ export function delete_component_template(id) {
 	return store.delete(`ct:${id}`);
 }
 
+// --- PDF files ---
+
+export function list_pdfs() {
+	const result = [];
+	for (const [key] of store.data.entries()) {
+		if (key.startsWith('pdf:')) result.push(store.get(key));
+	}
+	return result.sort((a, b) => a.display_name.localeCompare(b.display_name));
+}
+
+export function get_pdf(id) {
+	return store.get(`pdf:${id}`) ?? null;
+}
+
+export function set_pdf(pdf) {
+	store.set(`pdf:${pdf.id}`, pdf);
+}
+
+export function delete_pdf(id) {
+	return store.delete(`pdf:${id}`);
+}
+
 // --- Grid images ---
 
 export function list_grid_images() {