Add Todo module: SPA task manager with lists, priorities and due dates

- New todo.php SPA page with sidebar (smart views + user lists)
- modules/todo/api.php: REST API for lists and todos (CRUD, filters, stats)
- modules/todo/assets/todo.js: frontend (quick add, toggle done, modals)
- modules/todo/assets/todo.css: full light/dark theme styles
- pf_todo_lists + pf_todos tables added to schema_family.sql
- Integrated in header nav, home page cards, settings module list
- Translations added in fr/en/ca

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

docker/schema_family.sql

@@ -317,3 +317,27 @@ CREATE TABLE IF NOT EXISTS pf_memo_attachments (
   created_at    DATETIME DEFAULT CURRENT_TIMESTAMP,
   FOREIGN KEY (note_id) REFERENCES pf_memo_notes(id) ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+-- ─── Todo ─────────────────────────────────────────────────────────────────────
+CREATE TABLE IF NOT EXISTS pf_todo_lists (
+  id         INT AUTO_INCREMENT PRIMARY KEY,
+  name       VARCHAR(255) NOT NULL,
+  color      VARCHAR(20) DEFAULT '#3b82f6',
+  icon       VARCHAR(10) DEFAULT '📋',
+  position   INT DEFAULT 0,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+CREATE TABLE IF NOT EXISTS pf_todos (
+  id         INT AUTO_INCREMENT PRIMARY KEY,
+  list_id    INT DEFAULT NULL,
+  title      VARCHAR(500) NOT NULL,
+  notes      TEXT DEFAULT NULL,
+  due_date   DATE DEFAULT NULL,
+  priority   ENUM('none','low','medium','high') DEFAULT 'none',
+  done       TINYINT(1) DEFAULT 0,
+  done_at    DATETIME DEFAULT NULL,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  FOREIGN KEY (list_id) REFERENCES pf_todo_lists(id) ON DELETE SET NULL
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;