feat: config-driven environments (env vars + start scripts)

Add env var overrides matching main app pattern:
- CANTEEN_IMPORT_PORT — port override (default 8091)
- CANTEEN_IMPORT_DB_PATH — database path override
- CANTEEN_IMPORT_SEED_DIR — seed data directory override
- CANTEEN_IMPORT_UPLOAD_DIR — upload directory override

Create start scripts in repo:
- start.sh — production (default port 8091)
- start-dev.sh — development (port 8093, assets.dev.db)

Fix: dev clone now pulls from Gitea (not local prod dir)

web/server.py

@@ -79,9 +79,18 @@ def _list_backup_files() -> list[dict]:
 
 # ─── Config ──────────────────────────────────────────────────────────────────
 
-DEFAULT_DB_PATH = str(PROJECT_ROOT / "seed-data" / "assets.db")
-DEFAULT_SEED_DIR = str(PROJECT_ROOT / "seed-data")
-UPLOAD_DIR = Path("/tmp/canteen-import-uploads")
+DEFAULT_DB_PATH = os.environ.get(
+    "CANTEEN_IMPORT_DB_PATH",
+    str(PROJECT_ROOT / "seed-data" / "assets.db"),
+)
+DEFAULT_SEED_DIR = os.environ.get(
+    "CANTEEN_IMPORT_SEED_DIR",
+    str(PROJECT_ROOT / "seed-data"),
+)
+UPLOAD_DIR = Path(os.environ.get(
+    "CANTEEN_IMPORT_UPLOAD_DIR",
+    "/tmp/canteen-import-uploads",
+))
 REPORT_PATH = Path(DEFAULT_SEED_DIR) / "validation_report.md"
 HEADERS_FILE = Path(DEFAULT_SEED_DIR) / "headers_modified.csv"
 REFERENCE_FILE = Path(DEFAULT_SEED_DIR) / "reference_handbook.md"
@@ -603,7 +612,9 @@ if __name__ == "__main__":
     import uvicorn
 
     parser = argparse.ArgumentParser(description="Canteen Seed Import Web Server")
-    parser.add_argument("--port", type=int, default=8091, help="Port to listen on")
+    parser.add_argument("--port", type=int,
+                        default=int(os.environ.get("CANTEEN_IMPORT_PORT", "8091")),
+                        help="Port to listen on")
     parser.add_argument("--host", type=str, default="0.0.0.0", help="Host to bind to")
     args = parser.parse_args()