feat(projects): editable notes with edit stamp + NoteCard bubble component

- author-only note editing (PUT /projects/:id/notes/:noteId, strict schema,
  audit with old/new content); edits stamped via new edited_at column
  (migration 20260612160000) and shown as '· upraveno <datum>'
- note deletion tightened to admin-only server-side (was any projects.edit
  holder via direct API)
- new NoteCard component: chat-bubble note row (initials avatar, wrapping
  header, inline editor, actions in the bubble corner so they don't squeeze
  content on mobile), table-matching edit/delete icons
- Odin project detail carries the edited_at stamp; route-level tests cover
  author-edit, foreign-edit 403, validation, admin-only delete

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/services/projects.service.ts

@@ -283,3 +283,37 @@ export async function deleteProjectNote(projectId: number, noteId: number) {
   await prisma.project_notes.delete({ where: { id: noteId } });
   return note;
 }
+
+/**
+ * Author-only note edit: a note belongs to whoever wrote it (even admins
+ * edit only their own — editing someone else's words would falsify
+ * authorship; admins delete instead). Stamps edited_at for the UI marker.
+ */
+export async function updateProjectNote(
+  projectId: number,
+  noteId: number,
+  userId: number,
+  content: string,
+): Promise<
+  | null
+  | { error: string; status: number; note?: never }
+  | {
+      error?: never;
+      status?: never;
+      note: Awaited<ReturnType<typeof prisma.project_notes.update>>;
+      previousContent: string | null;
+    }
+> {
+  const note = await prisma.project_notes.findFirst({
+    where: { id: noteId, project_id: projectId },
+  });
+  if (!note) return null;
+  if (note.user_id !== userId) {
+    return { error: "Upravit lze pouze vlastní poznámku", status: 403 };
+  }
+  const updated = await prisma.project_notes.update({
+    where: { id: noteId },
+    data: { content, edited_at: new Date() },
+  });
+  return { note: updated, previousContent: note.content };
+}