feat(portal): M1 data model — Client, ClientAccessToken, Project.client_id

Client (customer org), ClientAccessToken (interim hashed magic-URL gate), and an
authoritative Project.client_id FK (client_name kept for display). New tables
auto-create via create_all; migrate_add_client_portal.py adds projects.client_id.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/migrate_add_client_portal.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""
+Database migration: Client Portal (M1).
+
+Adds the authoritative client link to projects:
+  - projects.client_id  (TEXT, nullable)  -> clients.id
+
+The `clients` and `client_access_tokens` tables are created automatically by
+SQLAlchemy `create_all` at app startup (they're brand-new tables), so this
+migration only handles the column that create_all won't add to an existing
+`projects` table.
+
+Run once per database:
+    docker exec terra-view-terra-view-1 python3 backend/migrate_add_client_portal.py
+"""
+
+import sqlite3
+from pathlib import Path
+
+
+def migrate():
+    possible_paths = [
+        Path("data/seismo_fleet.db"),
+        Path("data/sfm.db"),
+        Path("data/seismo.db"),
+    ]
+    db_path = next((p for p in possible_paths if p.exists()), None)
+    if db_path is None:
+        print(f"Database not found in any of: {[str(p) for p in possible_paths]}")
+        print("A fresh DB created via models.py will include projects.client_id automatically.")
+        return
+
+    print(f"Using database: {db_path}")
+    conn = sqlite3.connect(db_path)
+    cursor = conn.cursor()
+
+    cursor.execute("PRAGMA table_info(projects)")
+    existing = {row[1] for row in cursor.fetchall()}
+
+    if "client_id" not in existing:
+        try:
+            cursor.execute("ALTER TABLE projects ADD COLUMN client_id TEXT")
+            print("✓ Added column: projects.client_id (TEXT)")
+        except sqlite3.OperationalError as e:
+            print(f"✗ Failed to add projects.client_id: {e}")
+    else:
+        print("○ Column already exists: projects.client_id")
+
+    conn.commit()
+    conn.close()
+    print("\n✓ Client-portal migration complete.")
+    print("  Note: `clients` + `client_access_tokens` tables auto-create on app startup.")
+
+
+if __name__ == "__main__":
+    migrate()