feat: add issue templates for Gitea

Added three issue templates to improve issue tracking:
- Feature request template for new features and enhancements.
- Bug report template for reporting bugs and unexpected behavior.
- General issue template for issues that don't fit other categories.

Templates follow Gitea best practices with proper frontmatter metadata.
Each template includes clear sections with inline comments to guide users.

Updated CLAUDE.md with issue management and workflow documentation.

Closes #21

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

CLAUDE.md

@@ -37,6 +37,31 @@ Use format: `<type>/<description>` with kebab-case.
 
 DO NOT advertise Claude.
 
+## Issue Management
+
+Use the `tea` CLI (Gitea command-line tool) for issue operations.
+
+**Common commands**:
+
+- `tea issues list` - List all issues.
+- `tea issues <number>` - View details of a specific issue.
+- `tea issues create --title "<title>" --body "<description>"` - Create a new issue.
+- `tea issues close <number>` - Close an issue.
+
+**Reading issues**: Use `tea issues <number>` to read the full details of an issue before starting work.
+
+## Issue Workflow
+
+When working on an issue:
+
+1. Read the issue using `tea issues <number>` to understand requirements.
+2. Create a feature branch following the branch naming convention.
+3. Make commits following the conventional commit format.
+4. Submit a pull request when ready.
+
+**Important**: Never commit directly to `main`.
+All work must be done in a feature branch and submitted via pull request.
+
 ## Pull Request Management
 
 Use the `tea` CLI (Gitea command-line tool) for PR operations instead of `gh`.