docs: add AGENTS.md per module and unify ports to 70XX

- Add CLAUDE.md at root and AGENTS.md in apps/api, apps/indexer,
  apps/backoffice, crates/parsers with module-specific guidelines
- Unify all service ports to 70XX (no more internal/external split):
  API 7080, Indexer 7081, Backoffice 7082
- Update docker-compose.yml, Dockerfiles, config.rs defaults,
  .env.example, backoffice routes, bench.sh, smoke.sh

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

AGENTS.md

@@ -73,12 +73,14 @@ sqlx migrate add -r migration_name
 
 ### Docker Development
 
+`docker-compose.yml` est à la **racine** du projet (pas dans `infra/`).
+
 ```bash
 # Start infrastructure only
-cd infra && docker compose up -d postgres meilisearch
+docker compose up -d postgres meilisearch
 
 # Start full stack
-cd infra && docker compose up -d
+docker compose up -d
 
 # View logs
 docker compose logs -f api
@@ -226,24 +228,21 @@ pub struct BookItem {
 ```
 stripstream-librarian/
 ├── apps/
-│   ├── api/           # REST API (axum)
-│   │   └── src/
-│   │       ├── main.rs
-│   │       ├── books.rs
-│   │       ├── pages.rs
-│   │       └── ...
-│   ├── indexer/       # Background indexing service
-│   │   └── src/
-│   │       └── main.rs
-│   └── backoffice/    # Next.js admin UI
+│   ├── api/           # REST API (axum) — port 7080
+│   │   └── src/       # books.rs, pages.rs, thumbnails.rs, state.rs, auth.rs...
+│   ├── indexer/       # Background indexing service — port 7081
+│   │   └── src/       # worker.rs, scanner.rs, batch.rs, scheduler.rs, watcher.rs...
+│   └── backoffice/    # Next.js admin UI — port 7082
 ├── crates/
-│   ├── core/          # Shared config
+│   ├── core/          # Shared config (env vars)
 │   │   └── src/config.rs
 │   └── parsers/       # Book parsing (CBZ, CBR, PDF)
 ├── infra/
-│   ├── migrations/    # SQL migrations
-│   └── docker-compose.yml
-└── libraries/         # Book storage (mounted volume)
+│   └── migrations/    # SQL migrations (sqlx)
+├── data/
+│   └── thumbnails/    # Thumbnails générés par l'API
+├── libraries/         # Book storage (mounted volume)
+└── docker-compose.yml # À la racine (pas dans infra/)
 ```
 
 ### Key Files
@@ -251,8 +250,12 @@ stripstream-librarian/
 | File | Purpose |
 |------|---------|
 | `apps/api/src/books.rs` | Book CRUD endpoints |
-| `apps/api/src/pages.rs` | Page rendering & caching |
-| `apps/indexer/src/main.rs` | Indexing logic, batch processing |
+| `apps/api/src/pages.rs` | Page rendering & caching (LRU + disk) |
+| `apps/api/src/thumbnails.rs` | Thumbnail generation (triggered by indexer) |
+| `apps/api/src/state.rs` | AppState, Semaphore concurrent_renders |
+| `apps/indexer/src/scanner.rs` | Filesystem scan, rayon parallel parsing |
+| `apps/indexer/src/batch.rs` | Bulk DB ops via UNNEST |
+| `apps/indexer/src/worker.rs` | Job loop, watcher, scheduler orchestration |
 | `crates/parsers/src/lib.rs` | Format detection, metadata parsing |
 | `crates/core/src/config.rs` | Configuration from environment |
 | `infra/migrations/*.sql` | Database schema |
@@ -269,7 +272,7 @@ impl IndexerConfig {
     pub fn from_env() -> Result<Self> {
         Ok(Self {
             listen_addr: std::env::var("INDEXER_LISTEN_ADDR")
-                .unwrap_or_else(|_| "0.0.0.0:8081".to_string()),
+                .unwrap_or_else(|_| "0.0.0.0:7081".to_string()),
             database_url: std::env::var("DATABASE_URL")
                 .context("DATABASE_URL is required")?,
             // ...
@@ -298,4 +301,6 @@ fn remap_libraries_path(path: &str) -> String {
 - **Workspace**: This is a Cargo workspace. Always specify the package when building specific apps.
 - **Dependencies**: External crates are defined in workspace `Cargo.toml`, not individual `Cargo.toml`.
 - **Database**: PostgreSQL is required. Run migrations before starting services.
-- **External Tools**: The indexer relies on `unar` (for CBR) and `pdftoppm` (for PDF) being installed on the system.
+- **External Tools**: 4 system tools required — `unrar` (CBR page count), `unar` (CBR extraction), `pdfinfo` (PDF page count), `pdftoppm` (PDF page render). Note: `unrar` and `unar` are distinct tools.
+- **Thumbnails**: generated by the **API** service (not the indexer). The indexer triggers a checkup via `POST /index/jobs/:id/thumbnails/checkup` after indexing.
+- **Sub-AGENTS.md**: module-specific guidelines in `apps/api/`, `apps/indexer/`, `apps/backoffice/`, `crates/parsers/`.