docs: Pages site accuracy fixes + tools-table drift guard

[TMHSDigital]

Summary

From a Playwright review of the live GitHub Pages site:

• Corrected a factual error: the Windows notes claimed window capture matches "by exact title"; the real behavior (per src/utils/windows.ts and mcp-tools.json) is case-insensitive exact first, then substring, topmost match wins.
• Heading anchors: ids on all <h2>s so deep links like #tools work (previously dead).
• Favicon: inline SVG data URI — removes the 404 that was the page's only console error.
• 0.9.0 overwrite note: one sentence above the tools table documenting that tools refuse to replace an existing file at a caller-supplied output path without overwrite: true.
• OG/Twitter meta tags so shared links unfurl.
• New drift guard (src/__tests__/docs.test.ts): asserts the site's tools table and mcp-tools.json list exactly the same tool names, both directions. The table is hand-mirrored and nothing else checks it.

No version bump: docs and tests are not part of the published package (precedent: #49), and release.yml skips the already-tagged v0.9.0. Merging auto-triggers the Pages deploy (pages.yml fires on docs/**).

Testing

• Full gate green: build, typecheck, lint, 162 passed / 6 skipped — including the new docs-sync test.
• Negative check: deleting the reframe row makes the drift test fail with "tools missing from docs/index.html: reframe"; restored, it passes.
• Post-merge: will verify the live site (anchor scroll, zero console errors, corrected text) once Pages redeploys.

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