chore: add version management and changelog

- Add pyproject.toml with project metadata and version (1.1.0)
- Update config.py to read version from pyproject.toml
- Update main.py to use centralized version in FastAPI app
- Add CHANGELOG.md documenting v1.0.0 and v1.1.0 changes

Version is now the single source of truth in pyproject.toml and is
displayed in the health check endpoint and API docs.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.py

@@ -16,7 +16,7 @@ from typing import Dict, Any
 import logging
 from pathlib import Path
 
-from src.config import Settings, get_settings
+from src.config import Settings, get_settings, __version__
 from src.core.dependencies import verify_api_key
 
 # Configure logging
@@ -30,7 +30,7 @@ logger = logging.getLogger(__name__)
 app = FastAPI(
     title="Library Desk API",
     description="Coordination service for The Library system - HybridRAG queries, document ingestion, entity extraction, and mind map generation",
-    version="1.0.0",
+    version=__version__,
     docs_url="/docs",
     redoc_url="/redoc",
 )