chore: replace em dashes in source and output strings (#1283)

[prx-my]

Closes #1283.

What changed

• Replaced all 54 em dashes across 17 files under src/ (43 in emitted strings, 11 in comments/JSDoc):
  • Emitted clauses use : where a clause follows (e.g. 1 packument fetch failed: remediation guidance may be incomplete.), ;/period where a colon read poorly
  • HTML <title> separators use - (CVE Lite - <project>)
  • Comments and JSDoc use a plain -
• Updated the 8 tests that assert these strings exactly (multi-folder-scan, scanner-cache, html-reporter) after reading each assertion
• Also cleaned repo docs: README.md (10), docs/output-before-after.md (8), scripts/clean-dist.mjs (1). The docs/ sample output now matches current source (printers.ts colon, formatters.ts hyphens)
• Verified src/skills/content.ts output by eye (shipped AI-assistant docs, least coverage)

Verification

• grep -rn "—" src --include="*.ts" returns nothing
• npm test passes (163 suites, 2249 tests)
• npm run build is clean

Notes

• tests/output.test.ts:2944 intentionally keeps not.toContain("—") as the convention guard.
• Out of scope for this PR: website/docs/ (859) and examples/ (68) still contain em dashes; can be a follow-up docs PR.

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[prx-my]

Update: this branch has been refreshed with the latest main. It is no longer behind and now only awaits the required review/status checks before it can merge.