fix(docs): resolve .md links to page RelPermalink in render hook

Stripping the .md extension alone is not enough under Hugo pretty URLs.
A page rendered at /guides/DEPLOYMENT-OVERVIEW/ treats a bare relative
href like 'CLOUD-DEPLOY-WALKTHROUGH' as relative to that directory,
producing /guides/DEPLOYMENT-OVERVIEW/CLOUD-DEPLOY-WALKTHROUGH (404).

Switch to site.GetPage to look up the target page by its content path
(resolved relative to the current file's directory) and write its
RelPermalink into the href.  This gives an absolute path that is correct
in both the dev server and the GitHub Pages build (where --baseURL
injects the /Bose-SoundTouch/ prefix via RelPermalink automatically).

Also handles anchored links (OTHER.md#section) and falls back to
bare-stripped path when GetPage finds no match.

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

docs/layouts/_default/_markup/render-link.html

@@ -1,15 +1,41 @@
 {{- /*
-  Render hook: strip .md extension from internal links so that links
-  written as [foo](OTHER-PAGE.md) in Markdown source resolve to the
-  Hugo page URL instead of a raw .md path (which returns 404).
+  Render hook: resolve internal .md links to their Hugo RelPermalink.
 
-  This replaces the jekyll-relative-links behaviour from the old Jekyll
-  site without requiring changes to any content files.
+  Plain "strip .md" is not enough under pretty URLs: a page served at
+  /guides/DEPLOYMENT-OVERVIEW/ would resolve a bare relative href
+  "CLOUD-DEPLOY-WALKTHROUGH" to /guides/DEPLOYMENT-OVERVIEW/CLOUD-DEPLOY-WALKTHROUGH
+  (404).  Using site.GetPage gives the canonical /guides/CLOUD-DEPLOY-WALKTHROUGH/.
+
+  Handles:
+    - same-directory links:         CLOUD-DEPLOY-WALKTHROUGH.md
+    - cross-directory links:        ../architecture/DEVICE-LOCAL-INSTALL.md
+    - anchored links:               OTHER-PAGE.md#section
+    - external links (http/https):  passed through unchanged, opened in new tab
 */ -}}
 {{- $dest := .Destination -}}
 {{- $isAbs := or (strings.HasPrefix $dest "http://") (strings.HasPrefix $dest "https://") (strings.HasPrefix $dest "//") -}}
-{{- if and (not $isAbs) (strings.HasSuffix $dest ".md") -}}
-  {{- $dest = strings.TrimSuffix ".md" $dest -}}
+{{- if not $isAbs -}}
+  {{- /* Split off any fragment (#anchor) */ -}}
+  {{- $fragment := "" -}}
+  {{- $base := $dest -}}
+  {{- if strings.Contains $dest "#" -}}
+    {{- $parts := split $dest "#" -}}
+    {{- $base = index $parts 0 -}}
+    {{- $fragment = printf "#%s" (index $parts 1) -}}
+  {{- end -}}
+  {{- if strings.HasSuffix $base ".md" -}}
+    {{- $pathNoExt := strings.TrimSuffix ".md" $base -}}
+    {{- /* Resolve relative to the current content file's directory */ -}}
+    {{- $dir := "" -}}
+    {{- with .Page.File }}{{ $dir = .Dir }}{{ end -}}
+    {{- $resolved := site.GetPage (path.Join $dir $pathNoExt) -}}
+    {{- if $resolved -}}
+      {{- $dest = printf "%s%s" $resolved.RelPermalink $fragment -}}
+    {{- else -}}
+      {{- /* Fallback: strip .md (better than leaving the extension) */ -}}
+      {{- $dest = printf "%s%s" $pathNoExt $fragment -}}
+    {{- end -}}
+  {{- end -}}
 {{- end -}}
 <a href="{{ $dest }}"
   {{- with .Title }} title="{{ . }}"{{ end -}}