chore(deps): patch vite + yaml CVEs flagged by Dependabot

Resolves all six open Dependabot alerts:

vite 7.3.1 → 7.3.2 (npm audit fix, no breaking changes):
  - GHSA-p9ff-h696-f583 (high) — Arbitrary file read via dev server WS
  - GHSA-4w7w-66w2-5vf9 (medium) — Path traversal in optimized deps .map
  - GHSA-v2wj-q39q-566r (high) — server.fs.deny bypass via queries

yaml 2.x → 2.8.3 via package.json `overrides` block:
  - GHSA-48c2-rrv3-qjmp (moderate) — Stack overflow on deeply nested
    YAML collections. Pulled transitively by @astrojs/check (dev only)
    via the yaml-language-server chain. Override forces every yaml dep
    in the tree to the patched version without downgrading
    @astrojs/check (which `npm audit fix --force` would have done).

npm audit reports 0 vulnerabilities after the change. Astro check
clean, 372 tests pass, full build succeeds.

Author: chrisjohnleah

package-lock.json

@@ -37,5 +37,8 @@
     "tsx": "^4.21.0",
     "typescript": "^5.9.3",
     "vitest": "^4.1.2"
+  },
+  "overrides": {
+    "yaml": "^2.8.3"
   }
 }