Fix nutrition upload crash, persist runtime writes, serve API on its own domain

/api/upload/nutrition called json.dumps() in a module that never imported
json, so every request to it raised NameError, was swallowed by the broad
except, and came back as "500 Database import failed". Import json.

Persist the three directories the app writes to at runtime. Products added
through the UI are appended to data/seed_catalogs/*.json and retrained models
are written to app/intelligence/artifacts/*.joblib; both live inside the image,
so a redeploy silently discarded them. The paths now come from settings
(DATA_DIR / SEED_CATALOG_DIR / MODEL_ARTIFACTS_DIR) so a volume can be mounted
on them, and catalog_engine.save_catalog resolves against DATA_DIR instead of
a working-directory-relative "data/", which landed somewhere different
depending on where the process was started from.

Mounting those volumes would otherwise have made things worse: Docker seeds a
named volume from the image on first use, but a bind mount starts empty and
just hides what the image shipped. A bind mount on /app/data would have left
the API with no seed catalogs, so the next product added would write a JSON
file containing only that product. The image now keeps pristine copies at
/app/.bundled, and restore_bundled_assets() tops up whatever a freshly mounted
directory is missing at startup without overwriting anything already there.

Configure CORS for the split-domain deployment: the React app is served from
catalogue.nearle.ai.in and calls the API on mcp.catalogue.nearle.ai.in, so the
frontend origin has to be in API_CORS_ORIGINS. A wrong list fails only in the
browser while the server logs a healthy 200, so the effective origins are now
logged at startup with a warning when they are localhost-only.

Fix FRONTEND_DIST, which looked for a sibling "frontend/" directory that is
actually named "catalogue_frontend/", so the single-port unified-serving branch
could never activate even with a build sitting next to it.

Rebuild the Dockerfile on the frontend's multi-stage pattern: dependencies
resolve into a venv in a build stage, the runtime stage copies only that.
Adds PYTHONUNBUFFERED so startup errors reach Dokploy's log pane, a liveness
HEALTHCHECK (/api/health answers 200 even when Postgres is down, so a database
blip cannot restart-loop the container), and an overridable PORT. The CMD execs
uvicorn so SIGTERM reaches it rather than the sh wrapper.

Add "from __future__ import annotations" to ollama_service and image_search,
which used PEP 604 unions in runtime-evaluated signatures and so could not be
imported below Python 3.10.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/api/routers/upload.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import io
+import json
 import uuid
 import logging
 import pandas as pd

app/api/routers/user_products.py

@@ -9,6 +9,7 @@ from pydantic import BaseModel, Field
 from fastapi import APIRouter, Depends, HTTPException, File, UploadFile
 
 from app.api.deps import require_permission
+from app.infrastructure.settings import SEED_CATALOG_DIR
 
 from app.services.vector_store import (
     upsert_brand_products,
@@ -22,7 +23,10 @@ from app.services.s3_service import s3_service
 logger = logging.getLogger(__name__)
 router = APIRouter(prefix="/user/products", tags=["user_products"])
 
-SEED_DIR = Path(__file__).resolve().parents[3] / "data" / "seed_catalogs"
+# Written to by /add and /upload-file below. Comes from settings so it can be
+# pointed at a mounted volume - inside the image these writes are discarded on
+# every redeploy. See app/infrastructure/persistence.py.
+SEED_DIR = SEED_CATALOG_DIR
 
 
 class AddProductRequest(BaseModel):