Run oxfmt across repo, add format script and ignore config

Format all non-generated files with oxfmt via `vp fmt`. Add
.oxfmtignore to skip bindings/ and wasm-pack output. Add npm
format script and update DEVELOPMENT.md docs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/sponsors.yml

@@ -16,23 +16,23 @@ jobs:
         uses: JamesIves/github-sponsors-readme-action@v1
         with:
           token: ${{ secrets.SPONSORS_PAT }}
-          file: 'README.md'
+          file: "README.md"
           maximum: 1999
           template: '<a href="https://github.com/{{{ login }}}"><img src="{{{ avatarUrl }}}" width="50px" alt="User avatar: {{{ login }}}" /></a>&nbsp;&nbsp;'
           active-only: false
           include-private: true
-          marker: 'sponsors-base'
+          marker: "sponsors-base"
 
       - name: Generate Sponsors
         uses: JamesIves/github-sponsors-readme-action@v1
         with:
           token: ${{ secrets.SPONSORS_PAT }}
-          file: 'README.md'
+          file: "README.md"
           minimum: 2000
           template: '<a href="https://github.com/{{{ login }}}"><img src="{{{ avatarUrl }}}" width="80px" alt="User avatar: {{{ login }}}" /></a>&nbsp;&nbsp;'
           active-only: false
           include-private: true
-          marker: 'sponsors-premium'
+          marker: "sponsors-premium"
 
       # ⚠️ Note: You can use any deployment step here to automatically push the README
       # changes back to your branch.
@@ -41,4 +41,4 @@ jobs:
         with:
           branch: main
           force: false
-          folder: '.'
+          folder: "."