ci: improve dependabot grouping

Group wasm-bindgen with js-sys (lockstep, mirrors the existing napi
group) and group the JS tooling (oxlint, oxfmt, fallow) to cut weekly PR
noise. Add a chore commit-message prefix across all three ecosystems so
Dependabot PRs follow conventional commits and the release-drafter
autolabeler.

Author: BartWaardenburg

.github/dependabot.yml

@@ -6,9 +6,13 @@ updates:
       interval: weekly
     cooldown:
       default-days: 7
+    commit-message:
+      prefix: chore
     groups:
       napi:
         patterns: ["napi", "napi-derive", "napi-build"]
+      wasm-bindgen:
+        patterns: ["wasm-bindgen", "js-sys"]
     open-pull-requests-limit: 10
 
   - package-ecosystem: npm
@@ -17,9 +21,13 @@ updates:
       interval: weekly
     cooldown:
       default-days: 7
+    commit-message:
+      prefix: chore
     groups:
       napi-toolchain:
         patterns: ["@napi-rs/*"]
+      js-tooling:
+        patterns: ["oxlint", "oxfmt", "fallow"]
     ignore:
       # Self-published platform binaries; bumped in lockstep by the release
       # process to match the package version, never independently by Dependabot.
@@ -32,3 +40,5 @@ updates:
       interval: weekly
     cooldown:
       default-days: 7
+    commit-message:
+      prefix: chore