Add in-DB indexing script, benchmark results, schema names in presentation

- index_images_indb.py: new script indexing via VECTOR_EMBEDDING(CLIP_IMG)
  using a two-step INSERT+UPDATE to work around ORA-24816
- index_images_oracle.py / index_images.py: add timing output
- Presentation: schema names VECTORS_USER/VECTOR in diagram and comparison,
  ONNX expansion, HNSW index note on slide 11,
  indexing times updated from 3-run benchmark (avg: PG 12.1s, Ora 12.1s, InDB 13.6s)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

oravector-demo/backend/index_images_indb.py

@@ -0,0 +1,49 @@
+import os
+import time
+from dotenv import load_dotenv
+from db_oracle import get_connection_indb
+
+load_dotenv()
+
+PHOTOS_DIR = os.getenv("PHOTOS_DIR")
+
+def main():
+    conn = get_connection_indb()
+    cur = conn.cursor()
+
+    cur.execute("SELECT COUNT(*) FROM VECTOR.FOTO_VEKTOR")
+    print(f"Rows before: {cur.fetchone()[0]}")
+
+    files = [f for f in os.listdir(PHOTOS_DIR) if f.lower().endswith((".jpg", ".jpeg"))]
+    print(f"Found {len(files)} photos in {PHOTOS_DIR}")
+
+    start = time.time()
+    for i, filename in enumerate(files, 1):
+        filepath = os.path.join(PHOTOS_DIR, filename)
+        cur.execute("SELECT 1 FROM VECTOR.FOTO_VEKTOR WHERE filename = :1", (filename,))
+        if cur.fetchone():
+            print(f"[{i}/{len(files)}] Skipping {filename} (already indexed)")
+            continue
+        with open(filepath, "rb") as f:
+            blob_data = f.read()
+        # ORA-24816: Oracle cannot bind the same BLOB as both column value and
+        # VECTOR_EMBEDDING() input in one statement. Insert the BLOB first, then
+        # let Oracle compute the embedding from the stored data in a second step.
+        cur.execute(
+            "INSERT INTO VECTOR.FOTO_VEKTOR (filename, foto) VALUES (:1, :2)",
+            (filename, blob_data),
+        )
+        cur.execute(
+            """UPDATE VECTOR.FOTO_VEKTOR
+               SET foto_vek = VECTOR_EMBEDDING(CLIP_IMG USING foto AS data)
+               WHERE filename = :1""",
+            (filename,),
+        )
+        conn.commit()
+        print(f"[{i}/{len(files)}] Indexed {filename}")
+
+    elapsed = time.time() - start
+    print(f"Done in {elapsed:.1f} seconds.")
+
+if __name__ == "__main__":
+    main()