refactor: remove legacy environment variable aliases for configuration and concurrency settings

docs/DEPLOY.en.md

@@ -32,7 +32,6 @@ Config source (choose one):
 
 - **File**: `config.json` (recommended for local/Docker)
 - **Environment variable**: `DS2API_CONFIG_JSON` (recommended for Vercel; supports raw JSON or Base64)
-- Compatibility note: `CONFIG_JSON` is the legacy fallback variable; `DS2API_CONFIG_JSON` may also contain raw JSON directly
 
 Unified recommendation (best practice):
 
@@ -200,10 +199,10 @@ Notes:
 2. **Import** the project on Vercel
 3. **Set environment variables** (minimum required: one variable):
 
-   | Variable | Description |
-   | --- | --- |
-   | `DS2API_ADMIN_KEY` | Admin key (required) |
-   | `DS2API_CONFIG_JSON` | Config content, raw JSON or Base64 (optional, recommended) |
+| Variable | Description |
+| --- | --- |
+| `DS2API_ADMIN_KEY` | Admin key (required) |
+| `DS2API_CONFIG_JSON` | Config content, raw JSON or Base64 (optional, recommended) |
 
 4. **Deploy**
 
@@ -246,11 +245,8 @@ VERCEL_TEAM_ID=team_xxxxxxxxxxxx   # optional for personal accounts
 | Variable | Description | Default |
 | --- | --- | --- |
 | `DS2API_ACCOUNT_MAX_INFLIGHT` | Per-account inflight limit | `2` |
-| `DS2API_ACCOUNT_CONCURRENCY` | Alias (legacy compat) | — |
 | `DS2API_ACCOUNT_MAX_QUEUE` | Waiting queue limit | `recommended_concurrency` |
-| `DS2API_ACCOUNT_QUEUE_SIZE` | Alias (legacy compat) | — |
 | `DS2API_GLOBAL_MAX_INFLIGHT` | Global inflight limit | `recommended_concurrency` |
-| `DS2API_MAX_INFLIGHT` | Alias (legacy compat) | — |
 | `DS2API_ENV_WRITEBACK` | When `DS2API_CONFIG_JSON` is present, auto-write to `DS2API_CONFIG_PATH` and switch to file-backed mode after success (`1/true/yes/on`) | Disabled |
 | `DS2API_VERCEL_INTERNAL_SECRET` | Hybrid streaming internal auth | Falls back to `DS2API_ADMIN_KEY` |
 | `DS2API_VERCEL_STREAM_LEASE_TTL_SECONDS` | Stream lease TTL | `900` |