refactor(config): require explicit BZOD data directory

docs/CLI.md

@@ -284,3 +284,27 @@ bzod doctor
 * SECURITY.md
 * API.md
 * ARCHITECTURE.md
+
+---
+
+# Data Directory Configuration
+
+BZOD requires an explicit physical data directory root. There is **no implicit `./data` fallback**.
+
+### Configuration Precedence
+
+1. **CLI `--data-dir`** (Highest priority)
+   ```bash
+   bzod serve --data-dir /var/lib/bzod/data
+   bzod migrate --data-dir=/var/lib/bzod/data --dry-run
+   ```
+2. **Environment Variable `NX9_BZOD_DATA_DIR`**
+   ```bash
+   export NX9_BZOD_DATA_DIR=/var/lib/bzod/data
+   bzod serve
+   ```
+3. **Configuration File (`bzod.toml` / `config.toml`)**
+   ```toml
+   data_dir = "/var/lib/bzod/data"
+   ```
+4. **Error**: If no data directory is provided via CLI, `NX9_BZOD_DATA_DIR`, or config file, BZOD terminates with an actionable error.

docs/DOCKER-Deploy.md

@@ -100,7 +100,7 @@ services:
     environment:
       HOST: 0.0.0.0
       PORT: 8654
-      DATA_DIR: /app/data
+      NX9_BZOD_DATA_DIR: /app/data
       COOKIE_SECURE: "false"
 
     healthcheck:
@@ -204,13 +204,13 @@ BZOD Docker Container
 
 # Environment Variables
 
-| Variable      | Description        | Default   |
-| ------------- | ------------------ | --------- |
-| HOST          | Bind address       | 0.0.0.0   |
-| PORT          | Listen port        | 8654      |
-| DATA_DIR      | Database directory | /app/data |
-| COOKIE_SECURE | Secure cookies     | false     |
-| RUST_LOG      | Logging level      | info      |
+| Variable          | Description        | Default       |
+| ----------------- | ------------------ | ------------- |
+| HOST              | Bind address       | 0.0.0.0       |
+| PORT              | Listen port        | 8654          |
+| NX9_BZOD_DATA_DIR | Database directory | (required)    |
+| COOKIE_SECURE     | Secure cookies     | false         |
+| RUST_LOG          | Logging level      | info          |
 
 Production recommendation: