feat(utilities): add UniqueID helper, adopt AddModule

layouts/_partials/utilities/AddModule.html

@@ -0,0 +1,13 @@
+{{- $page := .page -}}
+{{- if not $page -}}
+	{{- $page = page -}}
+{{- end -}}
+{{ with .module }}
+	{{- $dependencies := $page.Scratch.Get "dependencies" -}}
+	{{- if reflect.IsSlice $dependencies -}}
+		{{- $dependencies = $dependencies | append . | uniq -}}
+	{{ else }}
+		{{- $dependencies = slice . -}}
+	{{ end }}
+	{{- $page.Scratch.Set "dependencies" $dependencies -}}
+{{ end }}

layouts/_partials/utilities/UniqueID.html

@@ -0,0 +1,48 @@
+{{/*
+    Returns a page-unique, build-stable element id of the form "<prefix>-UID-<n>", counting from 1.
+
+    Use this instead of hashing `now` (which changes the id on every build, so a page carrying the
+    component never renders byte-identically) and instead of `.Ordinal` (which restarts at 0 inside
+    an embedded RenderString, as the `example` shortcode performs, so ids collide).
+
+    The counter lives in the page's Store, namespaced per prefix, so each component type counts
+    independently. The counter is contiguous: every call consumes and emits one value. A caller may
+    still drop the id it was handed (Hinode's `nav.html`, for instance, renders no dropdown element
+    for `tab-type: buttons`), which leaves an apparent gap in the rendered document - the value was
+    used, just not on an element that carries an id.
+
+    The literal "UID" segment is deliberate and load-bearing: it keeps these ids out of the space
+    Hugo's `anchorize` can occupy. Hugo derives heading anchors with `autoHeadingIDType = 'github'`,
+    which lowercases and reduces the heading to [a-z0-9-_], and de-duplicates repeated headings by
+    appending "-1", "-2", ... A page with two "FAQ" headings therefore emits `faq` and `faq-1`, which
+    would collide head-on with a bare `faq-1` container id - Bootstrap resolves `data-bs-parent`
+    with `querySelector`, which would then bind the accordion to the heading. An uppercase segment
+    is unreachable for `anchorize`, so the collision cannot occur. Do not "simplify" it away.
+
+    A DOM id need only be unique within the document that carries it, so no attempt is made to be
+    unique across pages.
+
+    The counter is read and written non-atomically. That is safe as used, since Hugo renders a given
+    page's templates on a single goroutine - but never hand this partial a page other than the one
+    being rendered, as two concurrently rendered pages sharing a counter would race.
+
+    Arguments:
+      prefix  (string, required)  the id's leading segment, e.g. "panel"
+      page    (optional)          the page to anchor the counter to; defaults to the current page
+*/}}
+
+{{- $prefix := .prefix -}}
+{{- if not $prefix -}}
+    {{- errorf "partial [utilities/UniqueID.html] - missing required argument 'prefix'" -}}
+{{- end -}}
+
+{{- $page := .page -}}
+{{- if not $page -}}
+    {{- $page = page -}}
+{{- end -}}
+
+{{- $key := printf "hinode-uid-%s" $prefix -}}
+{{- $count := add (or ($page.Store.Get $key) 0) 1 -}}
+{{- $page.Store.Set $key $count -}}
+
+{{- return printf "%s-UID-%d" $prefix $count -}}