chore(deps): raise fast-uri and qs override floors past open advisories

[MBombeck]

The Dependency Audit job has been failing on every open PR — #892, #893 and #899 all show it red while everything else is green. It is not their fault: pnpm audit --prod --audit-level=high is red on main too. Six advisories, two transitive packages.

fast-uri 3.1.5 → 3.1.6 (4× high)
Percent-encoded scheme normalization and skipped IDN handling let a crafted URL read as a different host than the one it actually resolves to — the exact confusion class isPublicUrl exists to catch. Both copies arrive under ajv, pulled in by @hookform/resolvers and the MCP SDK.
GHSA-jqff-g426-hqxp, GHSA-5jgf-p345-68v8, GHSA-f65p-4m7j-42xc, GHSA-fph4-wmhf-6fwf

qs 6.15.3 → 6.16.0 (2× moderate)
Bracket-key comma parsing walks around arrayLimit, and an attacker-controlled isBuffer turns a request body into a hang. This copy is express 5's, reached through the MCP SDK's HTTP transport, so it sits on a request path rather than a build path. body-parser asks for ^6.15.2 and express for ^6.14.0, so 6.16.0 satisfies both without a major.
GHSA-x5fp-wj9c-mxmx, GHSA-4mjr-xmp4-gh2g

Both bounds go into pnpm-workspace.yaml the same way as the ones already there, with a comment naming the advisory and the path it arrives on. Same minor line in both cases, and the lockfile moves exactly two packages.

Verification

• pnpm audit --prod --audit-level=high → No known vulnerabilities found (was: 4 high, 2 moderate)
• pnpm typecheck → clean
• pnpm build → succeeds, 320 static pages
• pnpm test → 22510 passing, 12 skipped. One timing flake in timezone-explicit-formatter-guard.test.ts (5s timeout on the grep guard, cold cache on this machine); passes on its own in 5.9s and is unrelated to either package.

Once this is on main, rebasing #892/#893/#899 should turn their Dependency Audit green.

[MBombeck]

Same two floors, same versions, landed as part of #905 a couple of hours ago and merged with v1.38.5. Closing this one as already done rather than as wrong: it named exactly the right fixes. The lockstep guard that compares the workspace pins against the image's own install was widened in the same release, so a floor that is set in one place and not the other now fails loudly.