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-content.sx

@@ -76,6 +76,15 @@
         "sx provides ~80 built-in pure functions. They work identically on server (Python) and client (JavaScript).")
       (div :class "space-y-6" prims))))
 
+(defcomp ~docs-special-forms-content (&key forms)
+  (~doc-page :title "Special Forms"
+    (~doc-section :title "Syntactic constructs" :id "special-forms"
+      (p :class "text-stone-600"
+        "Special forms are syntactic constructs whose arguments are NOT evaluated before dispatch. Each form has its own evaluation rules — unlike primitives, which receive pre-evaluated values. Together with primitives, special forms define the complete language surface.")
+      (p :class "text-stone-600"
+        "Forms marked with a tail position enable " (a :href "/essays/tco" :class "text-violet-600 hover:underline" "tail-call optimization") " — recursive calls in tail position use constant stack space.")
+      (div :class "space-y-10" forms))))
+
 (defcomp ~docs-css-content ()
   (~doc-page :title "On-Demand CSS"
     (~doc-section :title "How it works" :id "how"

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")))))

sx/sx/nav-data.sx

@@ -8,6 +8,7 @@
   (dict :label "Components" :href "/docs/components")
   (dict :label "Evaluator" :href "/docs/evaluator")
   (dict :label "Primitives" :href "/docs/primitives")
+  (dict :label "Special Forms" :href "/docs/special-forms")
   (dict :label "CSS" :href "/docs/css")
   (dict :label "Server Rendering" :href "/docs/server-rendering")))