fix(docs): fix sponsor link baseURL and add git commit hash to footer

- Use relURL (no leading slash) for the sponsor link so it respects
  the /Bose-SoundTouch/ base path on GitHub Pages; absURL and relURL
  both ignore the base path when the input starts with /
- Inject HUGO_PARAMS_GITHASH (github.sha) via the docs workflow and
  forward it into the Hugo container via docker-compose.docs.yml +
  make dev-docs, so the deployed footer shows a clickable short hash
  linking to the exact commit
- Use site.Params.githash (global) instead of .Site.Params.githash
  because Hextra calls custom/footer.html with a dict context, not a
  page; .Site is nil in that scope
- Use substr not slice to trim the hash to 7 chars

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/docs.yml

@@ -33,6 +33,7 @@ jobs:
         run: hugo --source docs/ --minify --destination ../_site --baseURL "${{ steps.pages.outputs.base_url }}"
         env:
           HUGO_ENVIRONMENT: production
+          HUGO_PARAMS_GITHASH: ${{ github.sha }}
       - name: Upload artifact
         uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
         with:

Makefile

@@ -458,7 +458,7 @@ screenshots:
 # First run: make dev-docs-tidy  (downloads Hextra, writes docs/go.sum)
 # Then:      make dev-docs        (http://localhost:1313, live reload)
 dev-docs:
-	docker compose -f docker-compose.docs.yml up
+	HUGO_PARAMS_GITHASH=$(shell git rev-parse HEAD) docker compose -f docker-compose.docs.yml up
 
 dev-docs-tidy:
 	docker compose -f docker-compose.docs.yml run --rm hugo mod tidy --source docs/

docker-compose.docs.yml

@@ -27,6 +27,8 @@ services:
       # downloads Hextra once.
       - hugo-mod-cache:/root/.cache/hugo_cache
     working_dir: /src
+    environment:
+      - HUGO_PARAMS_GITHASH
 
 volumes:
   hugo-mod-cache:

docs/layouts/_partials/custom/footer.html

@@ -1,6 +1,6 @@
 <div class="hx:flex hx:w-full hx:items-center hx:justify-between hx:text-sm" style="padding-top: 2rem; padding-bottom: 2rem;">
   <a class="hx:inline-flex hx:items-center hx:gap-1.5 hx:text-gray-500 hx:dark:text-gray-400 hx:hover:text-pink-500 hx:dark:hover:text-pink-400 hx:transition-colors"
-     href="{{ "/sponsor" | absURL }}"
+     href="{{ "sponsor" | relURL }}"
      target="_blank"
      rel="noopener noreferrer">
     <span style="color: #ec4899;">
@@ -10,5 +10,8 @@
   </a>
   <span class="hx:text-xs hx:text-gray-500 hx:dark:text-gray-400">
     © 2026 <a class="hx:hover:underline" href="https://github.com/gesellix" target="_blank" rel="noopener noreferrer">Tobias Gesellchen</a>
+    {{- with site.Params.githash }}
+    · <a class="hx:font-mono hx:hover:underline" href="https://github.com/gesellix/Bose-SoundTouch/commit/{{ . }}" target="_blank" rel="noopener noreferrer" title="Built from commit {{ . }}">{{ substr . 0 7 }}</a>
+    {{- end }}
   </span>
 </div>