feat: replace Directus with custom Node.js GraphQL backend

Removes Directus 11 and replaces it with a lean, purpose-built backend:
- packages/backend/: Fastify v5 + GraphQL Yoga v5 + Pothos (code-first)
  with Drizzle ORM, Redis sessions (session_token cookie), argon2 auth,
  Nodemailer, fluent-ffmpeg, and full gamification system ported from bundle
- Frontend: @directus/sdk replaced by graphql-request v7; services.ts fully
  rewritten with identical signatures; directus.ts now re-exports from api.ts
- Cookie renamed directus_session_token → session_token
- Dev proxy target updated 8055 → 4000
- compose.yml: Directus service removed, backend service added (port 4000)
- Dockerfile.backend: new multi-stage image with ffmpeg
- Dockerfile: bundle build step and ffmpeg removed from frontend image
- data-migration.ts: one-time script to migrate all Directus/sexy_ tables

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

packages/backend/src/db/schema/gamification.ts

@@ -0,0 +1,94 @@
+import {
+  pgTable,
+  text,
+  timestamp,
+  integer,
+  real,
+  index,
+  pgEnum,
+  uniqueIndex,
+} from "drizzle-orm/pg-core";
+import { users } from "./users.js";
+import { recordings } from "./recordings.js";
+
+export const achievementStatusEnum = pgEnum("achievement_status", [
+  "draft",
+  "published",
+]);
+
+export const achievements = pgTable(
+  "achievements",
+  {
+    id: text("id").primaryKey().$defaultFn(() => crypto.randomUUID()),
+    code: text("code").notNull(),
+    name: text("name").notNull(),
+    description: text("description"),
+    icon: text("icon"),
+    category: text("category"),
+    required_count: integer("required_count").notNull().default(1),
+    points_reward: integer("points_reward").notNull().default(0),
+    status: achievementStatusEnum("status").notNull().default("published"),
+    sort: integer("sort").default(0),
+  },
+  (t) => [uniqueIndex("achievements_code_idx").on(t.code)],
+);
+
+export const user_achievements = pgTable(
+  "user_achievements",
+  {
+    id: integer("id").primaryKey().generatedAlwaysAsIdentity(),
+    user_id: text("user_id")
+      .notNull()
+      .references(() => users.id, { onDelete: "cascade" }),
+    achievement_id: text("achievement_id")
+      .notNull()
+      .references(() => achievements.id, { onDelete: "cascade" }),
+    progress: integer("progress").default(0),
+    date_unlocked: timestamp("date_unlocked"),
+  },
+  (t) => [
+    index("user_achievements_user_idx").on(t.user_id),
+    uniqueIndex("user_achievements_unique_idx").on(t.user_id, t.achievement_id),
+  ],
+);
+
+export const user_points = pgTable(
+  "user_points",
+  {
+    id: integer("id").primaryKey().generatedAlwaysAsIdentity(),
+    user_id: text("user_id")
+      .notNull()
+      .references(() => users.id, { onDelete: "cascade" }),
+    action: text("action").notNull(),
+    points: integer("points").notNull(),
+    recording_id: text("recording_id").references(() => recordings.id, {
+      onDelete: "set null",
+    }),
+    date_created: timestamp("date_created").notNull().defaultNow(),
+  },
+  (t) => [
+    index("user_points_user_idx").on(t.user_id),
+    index("user_points_date_idx").on(t.date_created),
+  ],
+);
+
+export const user_stats = pgTable(
+  "user_stats",
+  {
+    id: integer("id").primaryKey().generatedAlwaysAsIdentity(),
+    user_id: text("user_id")
+      .notNull()
+      .references(() => users.id, { onDelete: "cascade" }),
+    total_raw_points: integer("total_raw_points").default(0),
+    total_weighted_points: real("total_weighted_points").default(0),
+    recordings_count: integer("recordings_count").default(0),
+    playbacks_count: integer("playbacks_count").default(0),
+    comments_count: integer("comments_count").default(0),
+    achievements_count: integer("achievements_count").default(0),
+    last_updated: timestamp("last_updated").defaultNow(),
+  },
+  (t) => [uniqueIndex("user_stats_user_idx").on(t.user_id)],
+);
+
+export type Achievement = typeof achievements.$inferSelect;
+export type UserStats = typeof user_stats.$inferSelect;