docs: clarify environment variables force settings in docker-compose

- Add clear warnings that env vars FORCE settings and lock UI configuration
- Emphasize these are not defaults but permanent overrides
- Comment out optional service URLs to prevent accidental locking
- Clarify that almost all settings can be configured through the web UI
- Direct users to configure settings through web interface

This addresses issue #875 where users were confused about environment
variables preventing UI configuration changes.

docker-compose.yml

@@ -8,16 +8,41 @@ services:
     ports:
       - "5000:5000"
     environment:
-      # Web Interface Settings
+      # ============================================================================
+      # IMPORTANT: Almost all settings can be configured through the web interface
+      # (except for things like the web port).
+      #
+      # Environment variables FORCE settings and prevent ANY changes through the UI.
+      # These are NOT defaults - they are permanent overrides that lock the setting.
+      # Only use environment variables if you want to enforce specific settings
+      # that users should NEVER be able to change.
+      #
+      # After starting the container, configure your settings at:
+      # http://localhost:5000/settings
+      # ============================================================================
+
+      # REQUIRED: Core settings that must be set
       - LDR_WEB_PORT=5000
       - LDR_WEB_HOST=0.0.0.0
-      - LDR_LLM_PROVIDER=ollama
-      - LDR_LLM_OLLAMA_URL=http://ollama:11434
-
-      - LDR_SEARCH_ENGINE_WEB_SEARXNG_DEFAULT_PARAMS_INSTANCE_URL=http://searxng:8080
-
-      # Data directory configuration
       - LDR_DATA_DIR=/data
+
+      # ============================================================================
+      # OPTIONAL: Service endpoints for docker-compose setup
+      # WARNING: These will lock the settings and prevent changes through the UI!
+      # Uncomment these if you want to enforce these service endpoints.
+      # Otherwise, configure them through the web interface after startup.
+      # ============================================================================
+      # - LDR_LLM_OLLAMA_URL=http://ollama:11434
+      # - LDR_SEARCH_ENGINE_WEB_SEARXNG_DEFAULT_PARAMS_INSTANCE_URL=http://searxng:8080
+
+      # ============================================================================
+      # ADVANCED: Uncomment ONLY if you need to enforce/lock these settings
+      # WARNING: This will disable UI configuration for these settings!
+      # ============================================================================
+      # - LDR_LLM_PROVIDER=ollama              # Lock the LLM provider
+      # - LDR_LLM_MODEL=gemma3:12b              # Lock the model selection
+      # - LDR_LLM_OPENAI_API_KEY=sk-...        # Lock OpenAI API key
+      # - LDR_LLM_ANTHROPIC_API_KEY=sk-ant-... # Lock Anthropic API key
     volumes:
       - ldr_data:/data
       - ldr_scripts:/scripts