fix(issue_resolver): replace wide emoji regex for CodeQL py/overly-large-range

[rosspeili]

Description

Hotfix for CodeQL alert #3 on main after #144.

validate_commit_message used a single wide regex span (\U0001F300-\U0001FAFF) to detect emojis in commit subjects. CodeQL rule py/overly-large-range flags that pattern as overly permissive (character-class range may match unintended code points).

Change: replace EMOJI_PATTERN regex with explicit Unicode code-point ranges and a small _contains_emoji() helper. Behavior unchanged — commit subjects with emojis are still rejected. No API or manifest changes.

Closes CodeQL alert #3 when merged and rescanned.

---

Type of Change (Matches Issue Templates)

• Skill Proposal: New Skill
• Bug Report Fix: Non-breaking fix (static-analysis / regex safety; no runtime behavior change intended)
• Doc Fix: Documentation Update
• Framework Feature / RFC Updates: Core Framework Update

---

Checklist (all PRs)

• My code follows the Agent Code of Conduct.
• I have run python -m flake8 . and pytest tests/ locally (or the subset relevant to this change).
• CHANGELOG.md updated under [Unreleased] if this PR changes user-visible behavior — not required; internal implementation detail only
• examples/README.md is updated — N/A

---

New or updated skill

Skip — hotfix touches one helper in workflow.py only; no metadata, docs, or example changes.

---

Constitution & Safety

• Deterministic logic only; no new network, git, or LLM paths.
• Commit-message gate behavior preserved: emoji subjects still rejected, AI co-author rules unchanged.

---

Related Issues

• Follow-up to [issue_resolver]: universal workflow v0.2, examples, and release … #144 (introduced EMOJI_PATTERN in workflow.py)
• Resolves Code scanning alert #3 (py/overly-large-range)