feat: Add GitHub issue and PR templates (gt-599nf)

Add .github/ISSUE_TEMPLATE/ with bug_report.md and feature_request.md
templates. Add .github/PULL_REQUEST_TEMPLATE.md for PR submissions.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,35 @@
+---
+name: Bug Report
+about: Report a bug in Gas Town
+title: ''
+labels: bug
+assignees: ''
+---
+
+## Bug Description
+<!-- A clear description of what the bug is -->
+
+## Steps to Reproduce
+1.
+2.
+3.
+
+## Expected Behavior
+<!-- What you expected to happen -->
+
+## Actual Behavior
+<!-- What actually happened -->
+
+## Environment
+- **OS**:
+- **Go version**:
+- **Gas Town version**: (`gt version`)
+- **tmux version** (if applicable):
+
+## Logs / Error Output
+```
+<!-- Paste relevant logs or error messages -->
+```
+
+## Additional Context
+<!-- Any other context about the problem -->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,22 @@
+---
+name: Feature Request
+about: Suggest a new feature for Gas Town
+title: ''
+labels: enhancement
+assignees: ''
+---
+
+## Problem Statement
+<!-- What problem does this feature solve? -->
+
+## Proposed Solution
+<!-- Describe the feature you'd like -->
+
+## Alternatives Considered
+<!-- Any alternative solutions or features you've considered -->
+
+## Use Case
+<!-- How would you use this feature? -->
+
+## Additional Context
+<!-- Any other context, mockups, or examples -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,19 @@
+## Summary
+<!-- Brief description of changes -->
+
+## Related Issue
+<!-- Link to issue: Fixes #123 or Closes #123 -->
+
+## Changes
+<!-- Bullet list of changes -->
+-
+
+## Testing
+<!-- How did you test these changes? -->
+- [ ] Unit tests pass (`go test ./...`)
+- [ ] Manual testing performed
+
+## Checklist
+- [ ] Code follows project style
+- [ ] Documentation updated (if applicable)
+- [ ] No breaking changes (or documented in summary)