Port homepage, posts section, shortcodes; update hugo.toml menus

- content/_index.md: homepage with site description and callout examples
- content/posts/asw-vocabulary.md: ASW data-* attribute vocabulary reference
- content/posts/getting-started.md: ASW-Hugo setup guide (updated URLs)
- hugo.toml: add params, taxonomies, menus (main + docs sidebar), ToC settings
- layouts/partials/nav.html: dynamic Hugo menu rendering (was hardcoded)
- layouts/shortcodes/callout.html, wikilink.html: ported from asw-hugo theme

Closes: asw#17, asw#13, asw#11, asw#16
28 pages build clean, deploy confirmed at port 8000.

layouts/shortcodes/wikilink.html

@@ -0,0 +1,20 @@
+{{- /*
+  wikilink shortcode — renders an internal link with ASW data-wikilink attribute.
+  
+  Usage:
+    {{< wikilink "Display Text" "/path/to/page/" >}}
+  
+  Param 0 (required): display text
+  Param 1 (optional): href path. Defaults to /display-text-slugified/
+  
+  Examples:
+    {{< wikilink "My Note" >}}
+    → <a href="/my-note/" data-wikilink>My Note</a>
+    
+    {{< wikilink "My Note" "/vault/my-note/" >}}
+    → <a href="/vault/my-note/" data-wikilink>My Note</a>
+*/ -}}
+{{- $text := .Get 0 -}}
+{{- $slug := $text | lower | replace " " "-" -}}
+{{- $href := .Get 1 | default (printf "/%s/" $slug) -}}
+<a href="{{ $href | relURL }}" data-wikilink>{{ $text }}</a>