Add persistent PostgreSQL stack and SQLite migration

TelcoPortal-README.md

@@ -6,9 +6,8 @@ Management web portal for:
   eligibility, current owner, venue)
 - Internet connectivity at each restaurant venue
 
-Same deployment approach as TostaSklad/TostaPortal: a Docker container you run locally on this
-PC with Docker Desktop, with all data kept in a bind-mounted folder outside the container. See
-`README-Docker.md` for how to start/stop it.
+The production Docker stack runs the app with PostgreSQL and retains its database in a named
+Docker volume. See `README-Docker.md` for the initial SQLite import, startup, and backup steps.
 
 ## Folder layout
 
@@ -18,8 +17,8 @@ QWE Telco/
   README-Docker.md              <- Docker instructions (start here)
   TelcoPortal-README.md         <- this file
   TelcoPortal-source/           <- Flask app source (rebuilt into the Docker image)
-  TelcoPortal-data/
-    telco.db                    <- the SQLite database (both tables live in this one file)
+  data/
+    telco.db                    <- legacy SQLite file, used for the first import only
 ```
 
 ## Data model
@@ -31,13 +30,13 @@ Replacement, Current Owner, Venue.
 Expiration, Notes. This table starts empty - the source Excel file only had mobile phone data -
 add rows with the "+ Add Connection" button on the Internet Connectivity page as you go.
 
-There is no login. Anyone who can reach the URL (`http://localhost:8092/` by default) can view
-and edit both tables.
+The portal is available at `http://localhost:8092/` by default and requires a configured user
+login.
 
 ## How the mobile phone data was loaded
 
 The one-off migration script `TelcoPortal-source/import_excel.py` reads the source Excel file
-(`Mobilne telefony 20260901.xlsx`) and loads it into `TelcoPortal-data/telco.db`. This has
+(`Mobilne telefony 20260901.xlsx`) and loads it into the legacy SQLite database. This has
 **already been run once** to populate the database - the Excel file is not needed by the running
 app and can be archived/deleted.
 
@@ -77,4 +76,5 @@ the Edit button in the portal itself.
 
 ## Backups
 
-Copy or zip `TelcoPortal-data/telco.db` any time - that single file is the entire database.
+The production database is PostgreSQL. Use the `pg_dump` command documented in
+`README-Docker.md` to create a portable backup.