ci: auto-bump GRC badge cache-buster on Go changes

GitHub's camo image proxy caches README image URLs aggressively,
which can leave the GRC badge showing a stale "error" state even
after the upstream report has recovered. A new workflow rewrites
the badge URL's ?v= query param to the current commit SHA on any
push that touches Go sources, forcing camo to re-fetch. Also adds
a package doc comment on cmd/root.go and triggers the first bump.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: marzagao

.github/workflows/bump-grc-badge.yml

@@ -0,0 +1,36 @@
+name: Bump GRC badge cache-buster
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - '**/*.go'
+      - 'go.mod'
+      - 'go.sum'
+
+permissions:
+  contents: write
+
+jobs:
+  bump:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+
+      - name: Rewrite badge URL with current SHA
+        run: |
+          sed -i -E \
+            's|(goreportcard\.com/badge/github\.com/marzagao/aquadirector)\?v=[^)"]*|\1?v=${{ github.sha }}|g' \
+            README.md
+
+      - name: Commit if changed
+        run: |
+          if git diff --quiet README.md; then
+            echo "README already up to date"
+            exit 0
+          fi
+          git config user.name  'github-actions[bot]'
+          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
+          git add README.md
+          git commit -m 'chore: bump GRC badge cache-buster [skip ci]'
+          git push

README.md

@@ -2,7 +2,7 @@
 
 Monitor and control your reef aquarium from the terminal — all on your local network, no cloud required.
 
-[![Go](https://img.shields.io/badge/Go-1.25+-00ADD8?logo=go)](https://go.dev) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE) [![CI](https://github.com/marzagao/aquadirector/actions/workflows/ci.yml/badge.svg)](https://github.com/marzagao/aquadirector/actions/workflows/ci.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/marzagao/aquadirector)](https://goreportcard.com/report/github.com/marzagao/aquadirector)
+[![Go](https://img.shields.io/badge/Go-1.25+-00ADD8?logo=go)](https://go.dev) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE) [![CI](https://github.com/marzagao/aquadirector/actions/workflows/ci.yml/badge.svg)](https://github.com/marzagao/aquadirector/actions/workflows/ci.yml) [![Go Report Card](https://goreportcard.com/badge/github.com/marzagao/aquadirector?v=init)](https://goreportcard.com/report/github.com/marzagao/aquadirector)
 
 <img src="hack/demo.svg" width="600" alt="Demo" />
 

cmd/root.go

@@ -1,3 +1,4 @@
+// Package cmd implements the aquadirector CLI commands.
 package cmd
 
 import (