chore(deps): hold TypeScript at 5.x for the worker dependabot group

The grouped worker update bumps TypeScript to 7.x, but
openapi-typescript@7.13.0 — still the latest release — peer-requires
`typescript: ^5.x`. The resulting tree cannot resolve, so `npm ci` fails
and the PR has been red every week since 2026-06-15 (#440). `main` itself
is fine: cloudflare-worker/package.json pins typescript ^5.9.3. Only
dependabot's own tree is broken.

Verified by resolving both trees directly:

- with typescript ^7.0.2: ERESOLVE, "peer typescript@^5.x from
  openapi-typescript@7.13.0"
- with typescript held at ^5.9.3 and the group's other four bumps applied
  (@cloudflare/vitest-pool-workers 0.20.2, @cloudflare/workers-types
  5.20260804.1, vitest 4.1.10, wrangler 4.119.0): resolves cleanly

So ignoring major TypeScript bumps unwedges the group rather than merely
shrinking it. Remove the ignore once openapi-typescript supports
TypeScript 7.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E7Rma9m9unUYXYgpon6Rph

Author: claude

.github/dependabot.yml

@@ -55,6 +55,16 @@ updates:
     open-pull-requests-limit: 5
     commit-message:
       prefix: chore
+    # TypeScript is held at 5.x here. openapi-typescript@7.13.0 — still the
+    # latest — peer-requires `typescript: ^5.x`, so a major bump produces a
+    # tree npm cannot resolve and every `npm ci` in CI fails. Without this,
+    # the grouped update pulled TypeScript 7.x and wedged the worker
+    # dependabot PR from 2026-06-15 onward (#440), failing weekly.
+    # Remove this ignore once openapi-typescript supports TypeScript 7.
+    ignore:
+      - dependency-name: typescript
+        update-types:
+          - version-update:semver-major
     groups:
       worker-npm-dependencies:
         patterns: