docs: document CYCLONE_DB_URL, backup recipe, sub-project 2 completion

README.md

@@ -65,6 +65,29 @@ npm run build
 npm test
 ```
 
+## Persistence
+
+Parsed batches, claims, remittances, matches, and activity events are
+stored in a SQLite file at `~/.local/share/cyclone/cyclone.db` by
+default. The directory is auto-created on first run.
+
+To use a different location, set `CYCLONE_DB_URL`:
+
+```bash
+export CYCLONE_DB_URL=sqlite:///path/to/cyclone.db
+# or
+export CYCLONE_DB_URL=postgresql://user:pass@host:5432/cyclone
+```
+
+### Backup
+
+```bash
+sqlite3 ~/.local/share/cyclone/cyclone.db ".backup /path/to/backup.db"
+```
+
+This is safe to run while the backend is running (uses SQLite's online
+backup API).
+
 ## Project layout
 
 ```
@@ -100,11 +123,8 @@ npm test
 
 ## Roadmap
 
-This is **sub-project 1 of 4**. The other three are not in this build:
+Sub-project 2 (DB + reconciliation) is **shipped**. The other two:
 
-- **Sub-project 2 — DB + reconciliation.** Replace the in-memory store
-  with SQLite/Postgres; add 837P ↔ 835 reconciliation matching payouts to
-  original claims.
 - **Sub-project 3 — More 837P/835 features.** Additional 837P validation
   rules (REF*G1 enforcement, BHT06), 835 CAS deep-parsing, 999 ACK, and
   270/271 eligibility.