Challenge count in the README hero is not covered by the parity suite

[kOaDT]

Problem

tests/unit/challenge-parity.test.ts guards the challenge count in README.md and EDUCATORS.md, but 2 of the 4 places that state it slip through:

• README.md:13 — the hero line, the first number a visitor reads: 36 challenges across <b>web, API, ...</b>. Neither guard regex matches it (no "CTF", no "chapters").
• EDUCATORS.md:187 — .match() returns only the first hit, so only EDUCATORS.md:19 is actually asserted.

Adding the 37th challenge therefore passes CI with a stale "36" in the README headline.

Current guards

tests/unit/challenge-parity.test.ts:366 and :381

readme.match(/(\d+) CTF challenges across (\d+) chapters/); // → README.md:168 ✅
readme.match(/(\d+) chapters, (\d+) flags/);                // → README.md:186 ✅
educators.match(/all (\d+) challenges/);                    // → EDUCATORS.md:19 only

Fix

• Add an assertion covering the README hero line.
• Switch the EDUCATORS.md assertion to matchAll so every occurrence is checked.

⚠️ README.md:170 reads "8 tasks and 7 flags" about the TryHackMe room — that is not the challenge count. A blanket /(\d+) flags/ assertion will fail on it.

Acceptance

Commenting out one entry in prisma/flags.ts makes npm run test:unit fail and name both README.md:13 and EDUCATORS.md:187.