Migrate workflows to Blacksmith (#428)

Co-authored-by: blacksmith-sh[bot] <157653362+blacksmith-sh[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ env:
 jobs:
     changes:
         name: Detect Change Scope
-        runs-on: ubuntu-latest
+        runs-on: blacksmith-2vcpu-ubuntu-2404
         outputs:
             docs_only: ${{ steps.scope.outputs.docs_only }}
             docs_changed: ${{ steps.scope.outputs.docs_changed }}
@@ -169,7 +169,7 @@ jobs:
         name: Docs-Only Fast Path
         needs: [changes]
         if: needs.changes.outputs.docs_only == 'true'
-        runs-on: ubuntu-latest
+        runs-on: blacksmith-2vcpu-ubuntu-2404
         steps:
             - name: Skip heavy jobs for docs-only change
               run: echo "Docs-only change detected. Rust lint/test/build skipped."
@@ -178,7 +178,7 @@ jobs:
         name: Non-Rust Fast Path
         needs: [changes]
         if: needs.changes.outputs.docs_only != 'true' && needs.changes.outputs.rust_changed != 'true'
-        runs-on: ubuntu-latest
+        runs-on: blacksmith-2vcpu-ubuntu-2404
         steps:
             - name: Skip Rust jobs for non-Rust change scope
               run: echo "No Rust-impacting files changed. Rust lint/test/build skipped."
@@ -213,7 +213,7 @@ jobs:
         name: CI Required Gate
         if: always()
         needs: [changes, lint, test, build, docs-only, non-rust, docs-quality]
-        runs-on: ubuntu-latest
+        runs-on: blacksmith-2vcpu-ubuntu-2404
         steps:
             - name: Enforce required status
               shell: bash