refactor: centralize test utilities and standardize test patterns

[neekolas]

• Move test/helpers.go to pkg/testutils/db.go
• Add pkg/testutils/logger.go with TestLogger(t) using zaptest
• Replace logging.CreateLogger("console", "info") with testutils.TestLogger(t)
• Replace context.Background() with t.Context() in all test files
• Standardize t.Cleanup in api_test.go (remove defer ctx.cleanup pattern)
• Standardize require over assert in http_test.go

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Note

Centralize test utilities and standardize test patterns across packages

• Moves the test DB helper from test/helpers.go to pkg/testutils/db.go and adds a new TestLogger helper in pkg/testutils/logger.go to provide a standardized, test-bound zap logger.
• Replaces context.Background() with t.Context() and switches from assert to require in tests across api, db, delivery, installations, subscriptions, and xmtp packages.
• Updates Go toolchain from 1.25 to 1.26 in Dockerfile, devcontainer.Dockerfile, go.mod, and README.md.

^{Macroscope summarized bf652cf.}

[neekolas]

• ci: add concurrency limits to all workflows #100
• feat: migrate test infrastructure to xnet #98
• feat: add V4 d14n listener with payload format support #96
• refactor: replace local upstream protos with xmtpd imports #97
• feat: migrate to V4 binary topic format #94
• refactor: centralize test utilities and standardize test patterns #99 👈 (View in Graphite)
• chore: upgrade Go from 1.25 to 1.26 #93
• main

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[macroscopeapp]

Approvability

A prior Macroscope approval was dismissed. Re-evaluating bf652cf…

No code changes detected at 0de1f5f. Prior analysis still applies.

[neekolas]

Merge activity

• Apr 8, 1:04 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Apr 8, 2:16 AM UTC: Graphite rebased this pull request as part of a merge.
• Apr 8, 2:18 AM UTC: Graphite couldn't merge this PR because it was not satisfying all requirements (PR does not have required approvals).
• Apr 8, 5:03 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Apr 8, 5:04 PM UTC: @neekolas merged this pull request with Graphite.

Dismissing prior approval to re-evaluate bf652cf