fix: harden supply chain security (#255)

* fix: patch smol-toml and tsdown vulnerabilities

Update smol-toml 1.6.0→1.6.1 (DoS via recursive comment parsing) and
tsdown 0.21.2→0.21.5 (picomatch ReDoS + method injection).

* fix: pin all unpinned dependency versions in Dockerfile

Pins subfinder v2.13.0, WhatWeb v0.6.3 (switched from git clone to
release tarball), schemathesis 4.13.0, addressable 2.8.9,
claude-code 2.1.84, and playwright-cli 0.1.1 for reproducible builds.

* fix: pin GitHub Actions to commit SHAs for supply chain security

* fix: pin GitHub Actions to commit SHAs in beta and rollback workflows

.github/workflows/rollback.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout tags
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           fetch-depth: 0
 
@@ -58,7 +58,7 @@ jobs:
           echo "version=$VERSION" >> "$GITHUB_OUTPUT"
 
       - name: Setup Node.js
-        uses: actions/setup-node@v6
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
           node-version: 24
           registry-url: https://registry.npmjs.org
@@ -72,10 +72,10 @@ jobs:
         run: npm dist-tag ls @keygraph/shannon
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v4
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
 
       - name: Log in to Docker Hub
-        uses: docker/login-action@v4
+        uses: docker/login-action@b45d80f862d83dbcd57f89517bcf500b2ab88fb2 # v4.0.0
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
@@ -84,7 +84,7 @@ jobs:
         run: docker buildx imagetools inspect "keygraph/shannon:${{ steps.target.outputs.version }}"
 
       - name: Install cosign
-        uses: sigstore/cosign-installer@v4.1.0
+        uses: sigstore/cosign-installer@ba7bc0a3fef59531c69a25acd34668d6d3fe6f22 # v4.1.0
 
       - name: Verify Docker image signature before rollback
         run: |