chore: add GitHub templates and CI workflow (#7)

- Add issue templates (feature, bug, infra, docs)
- Add PR template
- Add CI workflow (lint, build, test)

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

Co-authored-by: Alexa Louise <YOUR_REAL_EMAIL@EXAMPLE.COM>
Co-authored-by: Claude <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/infra_task.md

@@ -0,0 +1,29 @@
+---
+name: Infrastructure Task
+about: CI/CD, deployment, DevOps work
+title: "[Infra] "
+labels: type:infra, team:infra, status:backlog
+assignees: ''
+---
+
+## Summary
+<!-- One-sentence description of the infra task -->
+
+## Scope
+- [ ] CI/CD pipeline
+- [ ] Deployment config
+- [ ] Monitoring/Observability
+- [ ] Security
+- [ ] Other:
+
+## Current State
+<!-- What exists now? -->
+
+## Desired State
+<!-- What should exist after this work? -->
+
+## Affected Services
+<!-- Which repos/services does this touch? -->
+
+## Rollback Plan
+<!-- How do we undo this if something goes wrong? -->