`db dump` fails against remote PostgreSQL 17: config.go missing `case 17` image mapping

[taijonsmith]

Describe the bug
supabase db dump fails with "server version mismatch" when the remote database is PostgreSQL 17. The CLI's Docker container uses pg_dump 15.6, which refuses to connect to a PG 17.6 server.

Root cause: internal/utils/config.go Load() switch only handles case 13, case 14, case 15 — there is no case 17. The Image field is tagged toml:"-" so users cannot override it via config.toml. The Validate() function accepts case 15, 17: as valid, so major_version = 17 is accepted in config — it just never assigns the correct Docker image.

The PG 17 Docker image (supabase/postgres:17.6.1.095) already exists on ECR and is referenced in the main branch Dockerfile, but it's not wired into config.go.

To Reproduce

1. Have a Supabase project running PostgreSQL 17
2. Set major_version = 17 in supabase/config.toml
3. Run supabase db dump
4. Error: pg_dump: error: aborting because of server version mismatch
   • server version: 17.6; pg_dump version: 15.6

Expected behavior
db dump should use a Docker image with pg_dump 17.x when major_version = 17 is configured, matching the remote server version.

Screenshots
N/A

System information

• Ticket ID: f08c1ad7d1624aeb8aa21b9cfe1debfd
• Version of OS: macOS 26.4
• Version of CLI: v2.84.5
• Version of Docker: v29.0.1
• Versions of services: N/A (remote-only, not using local dev)

Additional context

• config.go source references:
  • Load() image switch: https://github.com/supabase/cli/blob/main/internal/utils/config.go (search for case 15: in the DbImage / major version switch)
  • Validate() accepts 17: https://github.com/supabase/cli/blob/main/internal/utils/config.go (search case 15, 17:)
  • Image field: tagged toml:"-" — not user-configurable
• The fix appears to be ~2 lines: add a Pg17Image constant to constants.go and a case 17: branch in Load()
• Possibly related to supabase start uses PostgreSQL 17 instead of matching remote version (15.8), causing db diff incompatibility #3748, though that issue is about the inverse direction (db diff with local PG 17 vs remote PG 15)