Add Special Forms docs page at /docs/special-forms

Parses special-forms.sx spec into categorized form cards with syntax,
description, tail-position info, and highlighted examples. Follows the
same pattern as the Primitives page: Python helper returns structured
data, .sx components render it.

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

sx/sx/docs.sx

@@ -123,3 +123,40 @@
       :category cat
       :primitives (get primitives cat)))
     (keys primitives))))
+
+;; Build all special form category sections from a {category: [form, ...]} dict.
+(defcomp ~doc-special-forms-tables (&key forms)
+  (<> (map (fn (cat)
+    (~doc-special-forms-category
+      :category cat
+      :forms (get forms cat)))
+    (keys forms))))
+
+(defcomp ~doc-special-forms-category (&key category forms)
+  (div :class "space-y-4"
+    (h3 :class "text-xl font-semibold text-stone-800 border-b border-stone-200 pb-2" category)
+    (div :class "space-y-4"
+      (map (fn (f)
+        (~doc-special-form-card
+          :name (get f "name")
+          :syntax (get f "syntax")
+          :doc (get f "doc")
+          :tail-position (get f "tail-position")
+          :example (get f "example")))
+        forms))))
+
+(defcomp ~doc-special-form-card (&key name syntax doc tail-position example)
+  (div :class "border border-stone-200 rounded-lg p-4 space-y-3"
+    (div :class "flex items-baseline gap-3"
+      (code :class "text-lg font-bold text-violet-700" name)
+      (when (not (= tail-position "none"))
+        (span :class "text-xs px-2 py-0.5 rounded-full bg-green-100 text-green-700" "TCO")))
+    (when (not (= syntax ""))
+      (pre :class "bg-stone-50 rounded px-3 py-2 text-sm font-mono text-stone-700 overflow-x-auto"
+        syntax))
+    (p :class "text-stone-600 text-sm whitespace-pre-line" doc)
+    (when (not (= tail-position ""))
+      (p :class "text-xs text-stone-500"
+        (span :class "font-semibold" "Tail position: ") tail-position))
+    (when (not (= example ""))
+      (~doc-code :code (highlight example "lisp")))))