fuzz: Add cifuzz

.github/workflows/cifuzz.yml

@@ -0,0 +1,53 @@
+name: CIFuzz
+
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - ".github/workflows/cifuzz.yml"
+      - "fuzz/**"
+      - "multipart/**"
+      - "pyproject.toml"
+      - "python_multipart/**"
+      - "uv.lock"
+
+permissions: {}
+
+jobs:
+  # https://google.github.io/oss-fuzz/getting-started/continuous-integration/
+  Fuzzing:
+    runs-on: ubuntu-latest
+
+    permissions:
+      security-events: write
+
+    steps:
+      - name: Build Fuzzers
+        id: build
+        uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@675ddfb89ae1c614f1dfa99d18b91cd6d1d6b88b # master 2026-04-10
+        with:
+          oss-fuzz-project-name: "python-multipart"
+          language: python
+
+      - name: Run Fuzzers
+        uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@675ddfb89ae1c614f1dfa99d18b91cd6d1d6b88b # master 2026-04-10
+        with:
+          oss-fuzz-project-name: "python-multipart"
+          language: python
+          fuzz-seconds: 600
+          output-sarif: true
+
+      - name: Upload Crash
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
+        if: failure() && steps.build.outcome == 'success'
+        with:
+          name: artifacts
+          path: ./out/artifacts
+
+      - name: Upload Sarif
+        if: always() && steps.build.outcome == 'success'
+        uses: github/codeql-action/upload-sarif@014f16e7ab1402f30e7c3329d33797e7948572db # v4.31.3
+        with:
+          sarif_file: cifuzz-sarif/results.sarif
+          checkout_path: cifuzz-sarif