fix(docs): align every @docusaurus package on 3.10.2 so the Pages deploy builds again

[gHashTag]

Closes #1474

deploy-docs.yml is the only publisher of t27.ai (branch gh-pages). It has failed on every main push since 2026-10-04:

[ERROR] Error: Unable to build website for locale en.
  [cause]: Error: Invalid name=docusaurus-plugin-content-docs version number=3.10.0.

Dependabot (#1268, #1269, #1270) moved @docusaurus/core, theme-live-codeblock and tsconfig to 3.10.2 and left preset-classic, theme-mermaid, types and module-type-aliases on 3.10.0; Docusaurus refuses a mixed install. This PR pins all seven on 3.10.2 (npm install --save-exact); the lockfile shrinks because the duplicate 3.10.0 tree is gone. Last deploy on gh-pages: 840053f (2026-10-04), so nothing merged since has reached t27.ai.

{
  "version": 1,
  "head_sha": "0bdc7cfba2f5297ad727028f01f72d1934234d2b",
  "summary": "Align every @docusaurus package in docs/ on 3.10.2 so deploy-docs.yml builds again and t27.ai stops serving the 2026-10-04 build.",
  "changes": [
    "docs/package.json: preset-classic, theme-mermaid, types and module-type-aliases pinned to 3.10.2, matching core, tsconfig and theme-live-codeblock",
    "docs/package-lock.json: regenerated by npm install; the duplicate 3.10.0 plugin tree is removed"
  ],
  "tests": [
    {
      "command": "cd docs && npm install && npm run build",
      "result": "[SUCCESS] Generated static files in build, zero [ERROR] lines; on origin/main the same build fails with the Invalid version number error",
      "status": "passed",
      "evidence": "local run on 0bdc7cfba, Node 22, build rc 0, log checked for ERROR lines"
    }
  ],
  "limitations": [
    "apps/website is untouched; only the docs half of the Pages job was broken",
    "Dependabot can split the group again; grouping @docusaurus/* in dependabot.yml is a follow-up"
  ],
  "tags": [
    "docs",
    "deploy",
    "pages"
  ],
  "blog": {
    "title": "Why t27.ai stood still for three days",
    "summary": "A half-applied dependency bump left the docs on two Docusaurus versions, the Pages build refused them, and the site stopped updating.",
    "outline": [
      "Three dependabot PRs moved part of the Docusaurus packages to 3.10.2 while four sibling packages stayed on 3.10.0 in the same docs folder.",
      "Docusaurus checks that its plugins share one version, so every main push after 2026-10-04 failed the Pages build before anything was published.",
      "The fix pins all seven packages on 3.10.2; the local build that failed on main now generates the static files without a single error line."
    ]
  }
}

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