Remove iCloud Photos from borgmatic backup (#100)

## Summary
- Remove ~/Pictures from borgmatic source directories
- Update borgmatic and backup policy documentation
- Add Sifaka-Native Data section to clarify that photos (via Immich), music (via Navidrome), and video (via Jellyfin) are stored directly on Sifaka

## Deployment and Testing
- [ ] Run `mise run provision-indri -- --tags borgmatic --check --diff` to preview changes
- [ ] Run `mise run provision-indri -- --tags borgmatic` to apply
- [ ] Verify borgmatic config no longer includes ~/Pictures

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/100

docs/reference/storage/backups.md

@@ -25,7 +25,6 @@ Daily automated backups from [[indri]] to [[sifaka | Sifaka]] NAS.
 | `/opt/homebrew/var/forgejo` | Git repositories | Critical |
 | `~/.config/borgmatic` | Backup config | High |
 | `~/Documents` | Personal documents | High |
-| `~/Pictures` | Photos | Medium |
 
 ### Databases
 
@@ -34,6 +33,10 @@ Daily automated backups from [[indri]] to [[sifaka | Sifaka]] NAS.
 | miniflux | [[postgresql | pg.ops.eblu.me]] | pg_dump stream |
 | teslamate | [[postgresql | pg.ops.eblu.me]] | pg_dump stream |
 
+## Sifaka-Native Data
+
+Some data lives directly on [[sifaka]] rather than being backed up to it (photos via [[immich]], music via [[navidrome]], video via [[jellyfin]]). See [[sifaka]] for data protection details.
+
 ## What Is NOT Backed Up
 
 | Data | Reason |