Campaign assignments, ownership-based editing, and role-scoped data

- Add campaign_assignments table for user-to-campaign mapping
- Superadmin/managers can assign users to campaigns; visibility filtered by assignment/ownership
- Managers can only manage (tracks, assignments) on campaigns they created
- Budget controlled by superadmin only, with proper modal UI for editing
- Ownership-based editing for campaigns, projects, comments (creators can edit their own)
- Role-scoped dashboard and finance data (managers see only their campaigns' data)
- Manager's budget derived from sum of their campaign budgets set by superadmin
- Hide UI features users cannot use (principle of least privilege across all pages)
- Fix profile completion prompt persisting after saving (login response now includes profileComplete)
- Add post detail modal in campaign detail with thumbnails, publication links, and metadata
- Add comment inline editing for comment authors
- Move financial summary cards below filters on Campaigns page

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

server/db.js

@@ -178,6 +178,18 @@ function initialize() {
     );
   `);
 
+  // Campaign assignments (user-to-campaign junction table)
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS campaign_assignments (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      campaign_id INTEGER NOT NULL REFERENCES campaigns(id) ON DELETE CASCADE,
+      user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+      assigned_by INTEGER REFERENCES users(id),
+      assigned_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+      UNIQUE(campaign_id, user_id)
+    );
+  `);
+
   // ─── Column migrations ───
   // Helper: adds a column to a table if it does not already exist.
   function addColumnIfMissing(table, column, definition) {