Planka: add native Kanban module with proxy API and SPA board view

Adds modules/planka/api.php (PHP proxy to Planka at 10.200.33.10:1337), planka.css, and planka.php (full SPA with board selector, drag-and-drop cards, card modal with checklist). Registers planka in header nav, all 3 lang files, schema_family.sql and enables it for family 1.

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

docker/schema_family.sql

@@ -448,3 +448,14 @@ INSERT IGNORE INTO pf_pv_categories (name, color) VALUES
   ('Non classé','#64748b'),('Déco','#ec4899'),('Fonctionnel','#3b82f6'),
   ('Mécanique','#f59e0b'),('Jouets','#10b981'),('Outils','#ef4444'),
   ('Architecture','#8b5cf6'),('Art','#06b6d4');
+
+-- ─── Planka ───────────────────────────────────────────────────────────────────
+CREATE TABLE IF NOT EXISTS pf_planka_config (
+  id               INT NOT NULL DEFAULT 1,
+  project_id       VARCHAR(32),
+  admin_token      TEXT,
+  token_expires_at DATETIME,
+  active_board_id  VARCHAR(32),
+  updated_at       DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;