fix: [#934] Modify queue database connection when installing db driver

[hwbrzzl]

Summary

• Queue setup now reads both queue.connections.database.connection and queue.failed.database from DB_CONNECTION, removing the hardcoded postgres behavior.
• Database setup stubs now include DB_CONNECTION= so driver installers can persist the selected connection in .env.
• Added modify.Env(file, key, value) to rewrite existing .env keys (including duplicates) or append missing keys, while returning os.ErrNotExist when the file is absent.

Closes #934

Why

Installing a non-PostgreSQL driver could still leave queue database settings pinned to postgres, causing workers and failed-job logging to use the wrong database connection. The setup stubs now consistently defer to DB_CONNECTION, and the generated .env template always includes that key for installer updates.

The new modify.Env helper centralizes .env rewrites in setup flows so repeated runs replace stale values instead of drifting. It also fails fast when .env is missing, giving callers a concrete setup error to handle.

envPath := filepath.Join(t.TempDir(), ".env") _ = os.WriteFile(envPath, []byte("DB_CONNECTION=postgres\nAPP_ENV=local"), 0o644) // Before fix: setup could leave queue database settings effectively pinned to postgres. // After fix: setup rewrites DB_CONNECTION to the selected driver. _ = Env(envPath, "DB_CONNECTION", "mysql").Apply()

[codecov]

Codecov Report

❌ Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.20%. Comparing base (a770ad2) to head (5bd142c).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
queue/setup/stubs.go	0.00%	2 Missing ⚠️
database/setup/setup.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## master #1425 +/- ## ========================================== + Coverage 67.98% 68.20% +0.22%  ========================================== Files 354 357 +3 Lines 27521 27648 +127 ========================================== + Hits 18709 18857 +148  + Misses 7963 7940 -23  - Partials 849 851 +2 

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