docs(examples): replace education/LMS example with NYS Regents Chemistry dashboard

Replaces the generic coding-bootcamp LMS example with a real-world
government/education scenario: Physical Setting/Chemistry Regents exam
proctoring and score management for NYS public schools.

Covers three Django components:
- ExamSessionComponent — room roster, accommodation flags, timestamped
  check-in / absent / undo for proctors
- ScoreEntryComponent — per-part raw score entry (A:30, B-1:20, B-2:15,
  C:25 = 85 total) with ChemistryScoreSchema (Pydantic), automatic
  raw→scale conversion via per-administration ConversionChart DB lookup,
  and NYSED Level 1-5 performance badge
- ScoreAnalyticsComponent — pass/mastery rates, level distribution,
  safety-net student flagging, appeal roster, and one-click SIRS export
  payload for state reporting

Includes accurate Django models (RegentsSession, ConversionChart,
ExamRoom, StudentEnrollment, RegentsScore), template snippets,
parameterized pytest tests, and a note on the June 2026 exam format
transition (new 4-page data sheet replacing the 12-page CRT).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: fsecada01