build(runtime): embed the IANA tzdata in the binary

[guisea]

Summary

• Imports time/tzdata in cmd/api/main.go so time.LoadLocation and the TZ environment variable resolve on the runtime image, which is Alpine-based and ships no tzdata package.
• Without this, TZ has no effect and log timestamps are stuck in UTC regardless of what the operator sets.
• Adds about 450KB to the binary. Unset TZ still means UTC, same as before.
• Documents TZ in .env.example.

Fixes #48

Test plan

• go build ./... succeeds
• Ran the binary with TZ=Pacific/Auckland set and confirmed log timestamps reflect the local offset instead of UTC

Summary by CodeRabbit

• New Features

  • Added optional timezone configuration for log timestamps through the TZ environment variable.
  • Timezone values use IANA names and default to UTC when not specified.

• Documentation

  • Documented the TZ setting and supported timezone format in the environment configuration example.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 09481729-50cf-4ba1-8213-eb6590e38237

📥 Commits

Reviewing files that changed from the base of the PR and between 17860c9 and e85423f.

📒 Files selected for processing (2)

• .env.example
• cmd/api/main.go

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The API binary now embeds the IANA timezone database. The environment example documents the optional TZ variable for log timestamps and its UTC default.

Changes

Timezone support

Layer / File(s)	Summary
Embed timezone data and document TZ .env.example, cmd/api/main.go	The binary embeds the IANA timezone database. The environment example documents TZ, supported zone names, and the UTC default.

Priority: ➖ Normal

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: turbootzz

Merge Risk: ⚪ Minimal · up to e8542

The API can use configured IANA time zones for log timestamps in the Alpine runtime while retaining UTC when TZ is unset. No actionable merge risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: embedding the IANA timezone database in the runtime binary.
Linked Issues check	✅ Passed	For issue #48, cmd/api/main.go adds a blank import of time/tzdata. This embeds the IANA zoneinfo database and enables TZ values such as Pacific/Auckland on the Alpine runtime without a Docker …
Out of Scope Changes check	✅ Passed	The reported changes are limited to importing time/tzdata in cmd/api/main.go and documenting the related TZ setting in .env.example. Both changes directly implement issue #48. No unrelated cha…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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