Migrate backend from PocketBase to Directus

Full cutover: auth, users, collection and friendships now run on Directus
via @directus/sdk, with owner/visibility rules enforced by Directus
permissions.

- middleware: Directus session (directus_auth cookie) with token refresh
- /login is Directus (email normalized to lowercase), new /register page
  (first/last name, username) backed by public registration
- collection, friends and profile pages + all API endpoints ported;
  ownership and addressee-only accept/decline enforced by permissions
- display names use first_name/last_name everywhere (nav, friends, profile)
- PocketBase SDK, POCKETBASE_URL and pb_schema.json removed
- README and compose updated for DIRECTUS_URL

README.md

@@ -8,7 +8,8 @@ collection with Cardmarket price valuations, and share collections with friends.
 
 - [Astro](https://astro.build) (SSR, Node standalone adapter) — no UI framework
 - [Tailwind CSS v4](https://tailwindcss.com) + [basecoat-css](https://basecoatui.com)
-- [PocketBase](https://pocketbase.io) for database and authentication
+- [Directus](https://directus.io) for database, authentication and permissions
+  (via [`@directus/sdk`](https://www.npmjs.com/package/@directus/sdk))
 - [TCGdex API](https://api.tcgdex.net) (French locale) for card data, with an
   in-memory server-side cache (`src/lib/tcgdex-cache.ts`)
 
@@ -26,43 +27,41 @@ Node >= 22.12.
 
 ## Environment variables
 
-| Variable         | Description                                  | Default                              |
-| ---------------- | -------------------------------------------- | ------------------------------------ |
-| `POCKETBASE_URL` | URL of the PocketBase backend (auth + data)  | `https://pokeshare.namarusaja.me`    |
+| Variable       | Description                                 | Default                          |
+| -------------- | ------------------------------------------- | -------------------------------- |
+| `DIRECTUS_URL` | URL of the Directus backend (auth + data)   | `https://directus.namarusaja.me` |
 
 Read at **runtime** (`process.env`), so the same Docker image can be deployed
-against different PocketBase instances. For local dev, copy `.env.example` to
+against different Directus instances. For local dev, copy `.env.example` to
 `.env`. `HOST` and `PORT` are also honored by the standalone server.
 
 ## Docker
 
-Single container (external PocketBase):
+Single container (external Directus):
 
 ```sh
 docker build -t pokeshare .
-docker run -p 4321:4321 -e POCKETBASE_URL=https://pb.example.com pokeshare
+docker run -p 4321:4321 -e DIRECTUS_URL=https://directus.example.com pokeshare
 ```
 
-## Full stack (app + PocketBase)
-
-`docker-compose.yml` runs just the app; it expects an external PocketBase
-instance referenced by `POCKETBASE_URL` (see above). A schema export of the
-expected collections is kept at `pb_schema.json` for reference when setting
-up a new PocketBase instance (admin UI → Settings → Import collections).
+Or with the compose file:
 
 ```sh
-POCKETBASE_URL=https://pb.example.com docker compose up --build
+DIRECTUS_URL=https://directus.example.com docker compose up --build
 ```
 
 - The app listens on `4321`; expose it on your domain (Coolify: expose the
   `app` service, or use the plain Dockerfile build pack).
-- Accounts are managed from the PocketBase admin UI (`/_/`).
+- Collections, roles and permissions are managed from the Directus Data
+  Studio; public registration is enabled with the "App User" role.
 
 ## Structure
 
 - `src/pages/` — routes (`/`, `/search`, `/mycards`, `/card/[id]`,
-  `/series/[id]`, `/sets/[id]`, `/friends`, `/profile`) and JSON API endpoints
-  under `src/pages/api/`
-- `src/middleware.ts` — per-request PocketBase client + `pb_auth` cookie auth
-- `src/lib/` — TCGdex cache, collection pricing helpers, type theming
+  `/series/[id]`, `/sets/[id]`, `/friends`, `/profile`, `/login`, `/register`)
+  and JSON API endpoints under `src/pages/api/`
+- `src/middleware.ts` — Directus session (`directus_auth` cookie) with token
+  refresh, exposes `locals.directus` and `locals.user`
+- `src/lib/` — Directus client + types, TCGdex cache, collection pricing,
+  auth helper, type theming
 - `src/layouts/`, `src/components/` — base layout and nav