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>

.gitea/ISSUE_TEMPLATE/bug.md

@@ -0,0 +1,58 @@
+---
+name: "Bug Report"
+about: "Report a bug or unexpected behavior in the lambda interpreter."
+title: "fix: "
+ref: "main"
+assignees: []
+labels:
+  - bug
+---
+
+## Context
+
+<!--
+Describe what you were trying to do when you encountered the bug.
+Explain what you expected to happen.
+-->
+
+## Current Behavior
+
+<!--
+Describe what actually happened.
+Be specific about the incorrect behavior or error.
+-->
+
+## Steps to Reproduce
+
+<!--
+Provide step-by-step instructions to reproduce the issue.
+Include any relevant code, commands, or input.
+-->
+
+1.
+2.
+3.
+
+## Expected Behavior
+
+<!--
+Describe what should happen instead.
+-->
+
+## Environment
+
+<!--
+Provide relevant information about your environment.
+-->
+
+- Lambda version:
+- Go version:
+- Operating system:
+
+## Additional Context
+
+<!--
+Add any other context about the problem.
+Include error messages, logs, or screenshots if applicable.
+If none exist, omit this section.
+-->

.gitea/ISSUE_TEMPLATE/feature.md

@@ -0,0 +1,44 @@
+---
+name: "Feature Request"
+about: "Suggest a new feature or enhancement for the lambda interpreter."
+title: "feat: "
+ref: "main"
+assignees: []
+labels:
+  - enhancement
+---
+
+## Context
+
+<!--
+Describe the problem or limitation you're encountering.
+Explain why this feature would be valuable.
+-->
+
+## Proposed Solution
+
+<!--
+Describe your proposed solution or enhancement.
+Be specific about what you want to see implemented.
+-->
+
+## Alternatives Considered
+
+<!--
+List any alternative solutions or approaches you've considered.
+If none exist, omit this section.
+-->
+
+## Acceptance Criteria
+
+<!--
+List clear, testable criteria that define when this feature is complete.
+Use bullet points starting with •
+-->
+
+## Additional Context
+
+<!--
+Add any other context, screenshots, or examples about the feature request.
+If none exist, omit this section.
+-->

.gitea/ISSUE_TEMPLATE/general.md

@@ -0,0 +1,37 @@
+---
+name: "General Issue"
+about: "Create an issue that doesn't fit other templates."
+title: ""
+ref: "main"
+assignees: []
+labels: []
+---
+
+## Context
+
+<!--
+Describe the background and context for this issue.
+Explain why this issue exists.
+-->
+
+## Description
+
+<!--
+Provide a detailed description of what needs to be done.
+Be clear and specific about the requirements.
+-->
+
+## Acceptance Criteria
+
+<!--
+List clear, testable criteria that define when this issue is complete.
+Use bullet points starting with •
+If none exist, omit this section.
+-->
+
+## Additional Context
+
+<!--
+Add any other relevant information, links, or references.
+If none exist, omit this section.
+-->