fix(ci): fork-safe Week 11 autograder + PR body check

[lassebenni]

Summary

• Pin grade-assignment.yml to lassebenni/github-actions-fork@fix/allow-unsafe-pr-checkout-for-autograde (same as Week 13) so fork student PRs can be graded again after actions/checkout v6.
• Add pull_request_target to pr-body-check.yml so fork PRs are not stuck in action_required.

Why

Hannah's Week 11 PR (#14) fails at checkout with: "Refusing to check out fork pull request code from a pull_request_target workflow". The grader never runs on her latest commits.

Test plan

• Merge this PR
• Re-run Grade Assignment on PR Hannah N #14
• Confirm checkout succeeds and a fresh grade comment is posted

Made with Cursor

[github-actions]

📝 HackYourFuture auto grade

Assignment Score: 45 / 100 ❌

Status: ❌ Not passed
Minimum score to pass: 60
🧪 The auto grade is experimental and still being improved

Test Details

=== Week 11 Autograder ===
  ✓ PASS  found README.md
  ✓ PASS  found AI_ASSIST.md
  ✓ PASS  found week11-streamlit/app.py
  ✓ PASS  found week11-streamlit/pyproject.toml
  ✓ PASS  found week11-streamlit/uv.lock
  ✗ FAIL  missing required file: week11-streamlit/metric_definitions.md
  ✓ PASS  Level 1: required files (0/20 pts)
  ✓ PASS  root .gitignore excludes .env
  ✓ PASS  week11-streamlit/.env not committed
  ✓ PASS  app.py: no hardcoded Postgres credentials found
  ✓ PASS  Level 2: secrets hygiene (15/15 pts)
  ✓ PASS  app.py: imports a Postgres driver (sqlalchemy or psycopg2)
  ✓ PASS  app.py: reads credentials from the environment
  ✗ FAIL  app.py: raise NotImplementedError still present -- the headline KPIs panel is not implemented
  ✓ PASS  app.py: uses @st.cache_data
  ✓ PASS  Level 3: Streamlit app content (15/25 pts)
  ✗ FAIL  week11-streamlit/metric_definitions.md: empty
  ✓ PASS  Level 4: metric definitions (0/20 pts)
  ✓ PASS  README.md: dashboard link present under 'My submission'
  ✓ PASS  Level 5: Metabase dashboard documented (10/10 pts)
  ⚠ WARN  AI_ASSIST.md: present but brief or has leftover TODOs (902 chars, 4 TODO line(s))
  ✓ PASS  Level 6: AI assistance log (5/10 pts)

Score: 45 / 100  (passing: 60)  pass=false