feat: implement AtoCore Phase 0 + Phase 0.5 (foundation + PoC)

Complete implementation of the personal context engine foundation:
- FastAPI server with 5 endpoints (ingest, query, context/build, health, debug)
- SQLite database with 5 tables (documents, chunks, memories, projects, interactions)
- Heading-aware markdown chunker (800 char max, recursive splitting)
- Multilingual embeddings via sentence-transformers (EN/FR)
- ChromaDB vector store with cosine similarity retrieval
- Context builder with project boosting, dedup, and budget enforcement
- CLI scripts for batch ingestion and test prompt evaluation
- 19 unit tests passing, 79% coverage
- Validated on 482 real project files (8383 chunks, 0 errors)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/ingest_folder.py

@@ -0,0 +1,54 @@
+"""CLI script to ingest a folder of markdown files."""
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+# Add src to path
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from atocore.ingestion.pipeline import ingest_folder
+from atocore.models.database import init_db
+from atocore.observability.logger import setup_logging
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Ingest markdown files into AtoCore")
+    parser.add_argument("--path", required=True, help="Path to folder with markdown files")
+    args = parser.parse_args()
+
+    setup_logging()
+    init_db()
+
+    folder = Path(args.path)
+    if not folder.is_dir():
+        print(f"Error: {folder} is not a directory")
+        sys.exit(1)
+
+    results = ingest_folder(folder)
+
+    # Summary
+    ingested = sum(1 for r in results if r["status"] == "ingested")
+    skipped = sum(1 for r in results if r["status"] == "skipped")
+    errors = sum(1 for r in results if r["status"] == "error")
+    total_chunks = sum(r.get("chunks", 0) for r in results)
+
+    print(f"\n{'='*50}")
+    print(f"Ingestion complete:")
+    print(f"  Files processed: {len(results)}")
+    print(f"  Ingested: {ingested}")
+    print(f"  Skipped (unchanged): {skipped}")
+    print(f"  Errors: {errors}")
+    print(f"  Total chunks created: {total_chunks}")
+    print(f"{'='*50}")
+
+    if errors:
+        print("\nErrors:")
+        for r in results:
+            if r["status"] == "error":
+                print(f"  {r['file']}: {r['error']}")
+
+
+if __name__ == "__main__":
+    main()