QVAC-23542 fix: disable docs theme hotkey

[BrunoCampana]

What problem does this PR solve?

• The docs website search modal treats the typed letter d as a theme toggle after the Fumadocs version update (Aug 10).
• Users cannot reliably enter searches containing d, and the site unexpectedly flips between light and dark mode while they type.

How does it solve it?

• Disables Fumadocs' default plain d theme hotkey in the docs RootProvider.\n- Keeps theme support enabled while preventing search input text from toggling the page theme.\n

Preview / test

Check the bug in the prod env:
https://docs.qvac.tether.io
Navigate to the search and type "d"

Check that it's fixed in the testing env:
Now try to type "d" and you'll see it's working normally:
https://qvac-docs-staging-test-1-di1kk.kinsta.page

[github-actions]

Review Status

Current Status: ❌ PENDING
Approvals so far: none

Pending reviews: Needs 1 Management or Team Lead, and 1 more from Management, Team Lead, or Member.

[github-actions]

License compliance — clean

No new dependency license findings in this PR.

Warn-only (shadow) mode — this check does not block merges yet.

Updated automatically by the canonical license compliance workflow.

NOTICE presence (advisory)

Missing NOTICE (advisory, does not block):

• ./.github/actions/release-merge-guard
• ./packages/vla-ggml/sim/server
• ./packages/asr-ggml/benchmarks/server
• ./packages/embed-llamacpp/benchmarks/performance
• ./packages/embed-llamacpp/benchmarks/server
• ./packages/llm-llamacpp/benchmarks/performance
• ./packages/llm-llamacpp/benchmarks/server
• ./packages/inference-addon-cpp/mobile
• ./packages/ggml-coload-smoke
• ./packages/sdk/e2e
• ./packages/fabric/test/integration
• ./docs/website