fix(justfile): match codepoint ranges in docs-english, not \p{Script}

[anrysys]

Implementations disagree on whether \p{Greek} means Script or Script_Extensions. Under the latter, U+00B7 MIDDLE DOT - ordinary punctuation in README.md and USE-CASES.md - matches Greek, Han and Latin at once, so the check passed or failed purely on which grep happened to be installed: ugrep 7.8.4 flagged the tree, GNU grep did not. A rule that depends on the reader's toolchain is not a rule.

Explicit ranges say exactly what is meant, and read the same under every grep. All five scripts are still caught - verified against Cyrillic, Greek, Han, Hebrew and Arabic fixtures - the middle dot is not, and docs/i18n stays excluded.

What changed

Why

Checklist

• just check passes
• New behaviour has a SPEC- clause in docs/10-product/srs.md, naming its test
• Any decision with a rejected alternative has an ADR
• Documentation Maintenance Protocol has run
• No credential (.env, *.session) appears in the diff
• The Send Guard was not weakened

DOCS SYNC

DOCS SYNC
  Change type:
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  IDs added:
  IDs superseded:
  docs-check: