fix(ci): unblock CI — declare workspace root + bump pnpm to v10

Last 5 pushes (G-29..G-37) reported red on GitHub:
  ERROR  packages field missing or empty
  For help, run: pnpm help store

Two compounding causes:

1. `pnpm-workspace.yaml` listed `ignoredBuiltDependencies` only,
   no `packages` field. pnpm 10+ treats the file as a workspace
   marker and requires `packages` even for single-package roots.
   Without it `actions/setup-node@v4`'s `cache: pnpm` setup runs
   `pnpm store path --silent` which now refuses to enumerate the
   store before a workspace is resolved → setup fails before
   `pnpm install` even runs.

2. The CI matrix pinned pnpm v9 but my recent
   `pnpm.onlyBuiltDependencies` field in package.json (4a50784)
   is a pnpm 10+ schema. v9 either ignores it (silent drift) or
   warns; either way the local + CI environments diverge. Bumped
   both `pnpm/action-setup@v3 with: version` slots from 9 → 10
   so the runtime matches what we actually develop against.

Verified locally:
- pnpm install --frozen-lockfile → success (Done in 13.9s, pnpm v10.33.0)

This commit unblocks the prior 5 CI runs by retroactively making
the workspace declaration valid; pushing it triggers a fresh CI
that should land green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: B2JK-Industry

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v3
         with:
-          version: 9
+          version: 10
       - uses: actions/setup-node@v4
         with:
           node-version: 22
@@ -51,7 +51,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v3
         with:
-          version: 9
+          version: 10
       - uses: actions/setup-node@v4
         with:
           node-version: 22

pnpm-workspace.yaml

@@ -1,3 +1,10 @@
+# pnpm 10+ treats any pnpm-workspace.yaml as a workspace marker and
+# requires `packages` even when the repo is a single-package root.
+# Listing "." declares the root itself as the only workspace member,
+# which keeps `pnpm install` happy without splitting the repo.
+packages:
+  - "."
+
 ignoredBuiltDependencies:
   - sharp
   - unrs-resolver