fix(security): patch docs tar dependency

[0xjohnnydev]

The documentation site was resolving tar 7.5.16 through Tailwind's native build dependency. GitHub Dependabot reports a security alert for that version.

• Add a focused docs override for tar 7.5.18.
• Regenerate the docs lockfile so the resolved package and snapshot use the patched release.
• Keep the change limited to the docs dependency graph.

Validation

• npx --yes pnpm@9.0.4 install --lockfile-only --ignore-scripts from docs/
• git diff --check
• Confirmed docs/pnpm-lock.yaml has no tar@7.5.16 entry.

Definition of Done

• The visible docs tar alert feat(agent): add GUI-Owl model support #910 is mapped to this focused draft.
• The docs lock graph resolves tar 7.5.18, outside the reported vulnerable range.
• A human reviews and merges the draft; this automation does not advance drafts.
• GitHub closes the alert after the reviewed fix reaches the default branch.

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This draft is a duplicate of the existing focused docs dependency draft #2451. Review #2451 instead; this PR is retained as a draft for traceability and will not be advanced by the automation.

[0xjohnnydev]

Closing this draft because #2451 already owns the same docs tar dependency change. Keeping both would duplicate review and create lockfile conflicts. No code was merged; please continue review on #2451.