Add setup instructions to README for all three backends

Covers PostgreSQL database creation and schema setup, Oracle vectors_user
setup, and Oracle in-database ONNX model loading. Also updates project
structure to include the new sql/ directories.

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

README.md

@@ -70,6 +70,8 @@ vector-search-demo/
 ├── stop.sh                          # Stop all three backends
 ├── photos/                          # 116 JPEG photos (gitignored)
 ├── pgvector-demo/
+│   ├── sql/
+│   │   └── setup.sql                # Create table and HNSW index
 │   ├── backend/
 │   │   ├── .env                     # PostgreSQL credentials, photo path
 │   │   ├── db.py                    # PostgreSQL connection factory
@@ -79,6 +81,9 @@ vector-search-demo/
 │   └── frontend/
 │       └── index.html               # Search UI (served at /ui/)
 └── oravector-demo/
+    ├── sql/
+    │   ├── setup_vectors_user.sql   # Create vectors_user, table and HNSW index
+    │   └── setup_vector_schema.sql  # Create VECTOR user, load ONNX models, FOTO_VEKTOR table
     ├── backend/
     │   ├── .env                     # Oracle credentials, photo path
     │   ├── db_oracle.py             # Oracle connection factory
@@ -113,12 +118,8 @@ vector-search-demo/
 cd ~/docker/postgresql && docker compose up -d
 ```
 
-The `pgvector/pgvector:pg18` image includes pgvector pre-installed. The extension
+The `pgvector/pgvector:pg18` image includes pgvector pre-installed. See the
-must be activated once per database:
+[Setup from scratch](#setup-from-scratch) section for first-time database setup.
-
-```bash
-docker exec postgresql-database-1 psql -U dl -d vectors_demo -c "CREATE EXTENSION vector;"
-```
 
 ### Oracle 26ai (Podman container)
 
@@ -346,6 +347,93 @@ scores in percent.
 
 ---
 
+## Setup from scratch
+
+### 1. PostgreSQL
+
+**Start the container:**
+```bash
+cd ~/docker/postgresql && docker compose up -d
+```
+
+**Create the database:**
+```bash
+docker exec postgresql-database-1 psql -U dl -d pgdl -c "CREATE DATABASE vectors_demo;"
+```
+
+**Run the setup script** (creates the pgvector extension, `images` table, and HNSW index):
+```bash
+docker exec -i postgresql-database-1 psql -U dl -d vectors_demo -f - \
+  < pgvector-demo/sql/setup.sql
+```
+
+**Copy photos and index them:**
+```bash
+cd pgvector-demo/backend && python3 index_images.py
+```
+
+---
+
+### 2. Oracle 26ai — Python embedding backend
+
+**Configure vector memory** (once, requires Oracle restart):
+```bash
+podman exec oracle.free bash -c "sqlplus -s / as sysdba <<'EOF'
+ALTER SYSTEM SET vector_memory_size = 512M SCOPE=SPFILE;
+SHUTDOWN ABORT;
+STARTUP;
+EXIT;
+EOF"
+```
+
+**Run the setup script** (creates `vectors_user`, the `images` table, and HNSW index):
+
+Copy the script into the container and run it as SYSDBA:
+```bash
+podman cp oravector-demo/sql/setup_vectors_user.sql oracle.free:/tmp/
+podman exec oracle.free bash -c "sqlplus -s / as sysdba @/tmp/setup_vectors_user.sql"
+```
+
+**Index the photos:**
+```bash
+cd oravector-demo/backend && python3 index_images_oracle.py
+```
+
+---
+
+### 3. Oracle 26ai — in-database embedding backend
+
+This backend requires CLIP ONNX models loaded into the Oracle database. The setup
+is more involved and is intended to be done once by an administrator.
+
+**Prerequisites:**
+- CLIP ONNX model files (`clip_txt.onnx`, `clip_img.onnx`) present in the Oracle
+  VEC_DUMP directory inside the container (typically `/opt/oracle/dbs/vec_dump/`)
+- The `clip_txt.onnx` model must use **CLS-token pooling** (position 0), not the
+  standard EOS-token pooling — Oracle's ONNX validator rejects models that use
+  `ArgMax` on `input_ids`. See the [Oracle in-database embedding](#oracle-in-database-embedding)
+  section for details.
+
+**Run the setup script** (creates `VECTOR` user, loads ONNX models, creates `FOTO_VEKTOR` table):
+```bash
+podman cp oravector-demo/sql/setup_vector_schema.sql oracle.free:/tmp/
+podman exec oracle.free bash -c "sqlplus -s / as sysdba @/tmp/setup_vector_schema.sql"
+```
+
+**Populate `FOTO_VEKTOR`** with images and their vectors (run as VECTOR user in SQL):
+```sql
+-- Example: insert one photo with its CLIP_IMG embedding
+INSERT INTO vector.foto_vektor (filename, foto, foto_vek)
+VALUES (
+    'photo.jpg',
+    TO_BLOB(BFILENAME('VEC_DUMP', 'photo.jpg')),
+    VECTOR_EMBEDDING(CLIP_IMG USING TO_BLOB(BFILENAME('VEC_DUMP', 'photo.jpg')) AS data)
+);
+COMMIT;
+```
+
+---
+
 ## Running the applications
 
 ### Start all backends