docs: Add PR template to .github/

[YaronZaki]

Problem Statement

No pull request template exists in .github/. Contributors lack guidance on PR description format, checklist items, and review expectations. Only ISSUE_TEMPLATE/ exists with bug_report.md, feature_request.md, and custom.md.

Evidence

# .github/ directory contents:
# ISSUE_TEMPLATE/  (bug_report.md, feature_request.md, custom.md)
# workflows/       (ci.yml, cd.yml, etc.)
# No pull_request_template.md

Impact

Medium — contributor experience. PRs arrive with inconsistent descriptions. Contributors are unsure what information to include. Reviewers must ask the same questions repeatedly ("what testing did you do?", "does this need docs?").

Proposed Solution

Create .github/pull_request_template.md with sections: Description, Related Issue, Change Type (feat/fix/docs/refactor/test/ci), Testing Done, Screenshots (if UI), Checklist (tests pass, docs updated, linted, PR linked to issue).

Acceptance Criteria

• .github/pull_request_template.md created
• Template includes description, related issue, change type, testing, checklist sections
• Uses HTML comments for hidden guidance that doesn't appear in rendered PR
• Checklist items match project conventions (pylint, pytest, poetry)

File Map

• .github/pull_request_template.md — New file

Testing Strategy

• Manual: Open a test PR, verify template auto-populates the description field.

Security Considerations

No security impact.

Definition of Done

• File created and committed
• Template verified working
• PR linked and merged

Getting Started

Suggested first steps: (1) Review existing ISSUE_TEMPLATE/ files for project conventions, (2) Create PR template with standard sections, (3) Add HTML comments for guidance.
Estimated time: 0.5 hours

---

Labels: open-source, good-first-issue
Priority: Medium
Difficulty: Beginner
Estimated Effort: 0.5h