refactor: remove unused web UI port configuration

The web UI (docs/index.html, portfolio.html) exists but is not served
in API mode. Removing the port configuration to eliminate confusion.

Changes:
- Remove port 8888 mapping from docker-compose.yml
- Remove WEB_HTTP_PORT from .env.example
- Update Dockerfile EXPOSE to only port 8080
- Update CHANGELOG.md to document removal

Technical details:
- Web UI static files remain in docs/ folder (legacy from batch mode)
- These were designed for JSONL file format, not the new SQLite database
- No web server was ever started in entrypoint.sh for API mode
- Port 8888 was exposed but nothing listened on it

Result:
- Cleaner configuration (1 fewer port mapping)
- Only REST API (8080) is exposed
- Eliminates user confusion about non-functional web UI

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Removed
+- **Web UI Port** - Removed unused web dashboard port configuration
+  - Removed port 8888 from docker-compose.yml (not implemented)
+  - Removed WEB_HTTP_PORT from .env.example
+  - Removed port 8888 from Dockerfile EXPOSE
+  - Web UI static files exist in docs/ but are not served in API mode
+  - Only port 8080 (REST API) is now exposed
+
 ## [0.3.0] - 2025-10-31
 
 ### Added - API Service Transformation