Add Dagster orchestration and reduce active brands in backend

README.md

@@ -52,6 +52,58 @@ uvicorn app.main:app --reload --port 8000
 Then open http://localhost:8000/docs for interactive API docs, or run the
 frontend (`../frontend/README.md`) to use the React UI.
 
+## Active brands (development working set)
+
+One setting decides which brands the application and every pipeline work on:
+
+```
+# backend/.env
+ACTIVE_BRANDS=Amul,Cadbury,Hindustan Unilever
+```
+
+**Blank or unset means every brand is active** - that is the production default
+and the way to turn the feature off.
+
+Nothing is deleted when it is set. The other `brand_*` tables and their
+embeddings stay in Postgres untouched; they simply stop being discovered.
+Everything downstream inherits it, because the whole app funnels through two
+functions in `app/services/vector_store.py`
+(`list_available_brands` and `_list_brand_table_suffixes`):
+
+```
+ACTIVE_BRANDS
+     |
+     +-- /api/brands, /api/products, /api/search, /api/suggest
+     +-- RAG chat and the query_intent brand index
+     +-- MCP tools
+     +-- nutrition enrichment, store intelligence, analytics
+     +-- the boot auto-seed and the 300s brand reconcile
+     +-- every Dagster asset and partition
+```
+
+Going from 3 brands to 5, 10 or all of them is an edit to this one line - no
+code changes. Catalogs for inactive brands live in
+`data/seed_catalogs/archive/`, which the loader still reads, so re-activating a
+brand does not require moving files back.
+
+Names resolve through the brand aliases, so `ACTIVE_BRANDS=Tata` activates
+`brand_hindustan_unilever` - the same table an ingest of Tata products targets.
+
+## Orchestration (Dagster)
+
+Ingestion, enrichment, embedding and ML training can be run as a Dagster asset
+graph, with lineage, retries and run history. It is a **development tool** -
+FastAPI still serves every request and nothing in a request path touches it.
+
+```
+pip install -r requirements-orchestration.txt
+DAGSTER_HOME="$(pwd)/orchestration/.dagster_home"   dagster dev -m orchestration.definitions -p 3030
+```
+
+See `orchestration/README.md`. Note that it pins itself to the **local**
+database and refuses to write to a remote one, because `backend/.env` points at
+production.
+
 ## Authentication
 
 Reads are public; the 18 write/compute endpoints require a credential, enforced