feat: bump hermes-agent 0.2.0 → 0.3.0 + auto-update CI

- Update package.nix to v0.3.0 (NousResearch/hermes-agent v2026.3.17)
- Add scripts/update-pins.sh — checks latest stable release, prefetches, validates build
- Add .github/workflows/update-pins.yml — runs every 6h + manual dispatch
- Pattern follows nix-openclaw's yolo-update approach

.github/workflows/update-pins.yml

@@ -0,0 +1,30 @@
+name: Update Hermes Agent Pins
+
+on:
+  schedule:
+    # Check every 6 hours — hermes-agent doesn't release as often as openclaw
+    - cron: "15 */6 * * *"
+  workflow_dispatch: {}
+
+permissions:
+  contents: write
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v13
+
+      - name: Run updater
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          git config user.name "nix-hermes-agent-bot"
+          git config user.email "bot@nix-hermes-agent.local"
+          scripts/update-pins.sh