docs: add Issue Management guidelines to CONTRIBUTING.md

[0xaskr]

Summary

• Add ## Issue Management section to CONTRIBUTING.md covering title prefix convention, priority definitions, label taxonomy, issue lifecycle, Epic/Sub-issue conventions, and Issue Types usage
• New labels created: design-proposal, cpu-ref

Test plan

• Review the new section reads clearly and is consistent with existing CONTRIBUTING.md style
• Verify new labels appear in the repo label list

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Added issue management section to contributor guidelines establishing GitHub issue title prefix conventions ([Bug], [Feature], [Epic], [Perf], [Design]), priority level requirements (P0/P1/P2), standardized labeling, and comprehensive issue lifecycle rules covering epic and sub-issue management.

[coderabbitai]

📝 Walkthrough

Walkthrough

Added "Issue Management" section to CONTRIBUTING.md establishing GitHub issue title prefix conventions ([Bug], [Feature], [Epic], [Perf], [Design]), priority labeling requirements (P0, P1, P2), required label categories, lifecycle flow documentation, and rules for Epic/sub-issue management.

Changes

Cohort / File(s)	Summary
Documentation - Issue Management Guidelines CONTRIBUTING.md	Added comprehensive issue management section with mandatory title prefix conventions, priority level definitions and auto-defaulting to P2, required label specifications including special types (epic, performance, design-proposal, cpu-ref), lifecycle flow rules with Closes #N`` syntax, and Epic/sub-issue relationship requirements.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• primatrix/pallas-kernel#162 — Also modifies CONTRIBUTING.md with overlapping issue labeling and contribution workflow rules.

Poem

🐰 The warren's wisdom grows today,
With labels guiding issues' way,
P0 through P2, in order neat,
[Bug] and [Feature], oh how sweet!
Our community's path is now defined,
Contributions perfectly aligned! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and clearly describes the main change: adding Issue Management guidelines to CONTRIBUTING.md, which is the primary purpose of this 58-line documentation addition.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/issue-management

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[gemini-code-assist]

Code Review

This pull request introduces a comprehensive 'Issue Management' section to the CONTRIBUTING.md file, detailing title conventions, priority levels, labeling, and the issue lifecycle. The review feedback identifies missing title prefixes for documentation and questions to ensure consistency with the stated rules, and suggests refining the response time description for P2 priority issues to better align with the temporal definitions used for other priorities.

[gemini-code-assist]

The 'Title Convention' table is missing prefixes for the documentation and question labels, which are listed as 'Type labels' in the Labels section (line 130). Since the guide states that all issue titles must start with a type prefix, these should be explicitly defined to ensure consistency and guide contributors correctly.

Suggested change

	| Prefix | Usage | Label |
	|--------|-------|-------|
	| `[Bug]` | Bug report | `bug` |
	| `[Feature]` | Feature request | `enhancement` |
	| `[Epic]` | Large milestone or roadmap | `epic` |
	| `[Perf]` | Performance issue or optimization | `performance` |
	| `[Design]` | Kernel design proposal | `design-proposal` |
	| Prefix | Usage | Label |
	|--------|-------|-------|
	| [Bug] | Bug report | bug |
	| [Feature] | Feature request | enhancement |
	| [Epic] | Large milestone or roadmap | epic |
	| [Perf] | Performance issue or optimization | performance |
	| [Design] | Kernel design proposal | design-proposal |
	| [Docs] | Documentation improvement | documentation |
	| [Question] | General question or clarification | question |

[gemini-code-assist]

In the Priority table, 'Planned' is listed as a 'Response Time' for P2 issues. This term describes a status rather than a temporal expectation. Consider using a more specific time-based description to align with the 'Immediate' and 'Start within a week' values used for P0 and P1.

Suggested change

	| Priority | Meaning | Response Time |
	|----------|---------|---------------|
	| `P0` | Blocking — affects core functionality or CI | Immediate |
	| `P1` | Important — must complete in current iteration | Start within a week |
	| `P2` | Improvement — can be scheduled for later | Planned |
	| Priority | Meaning | Response Time |
	|----------|---------|---------------|
	| P0 | Blocking — affects core functionality or CI | Immediate |
	| P1 | Important — must complete in current iteration | Start within a week |
	| P2 | Improvement — can be scheduled for later | Best effort / Next iteration |