Add Isomorphism as top-level section in sx-docs

Move isomorphic architecture roadmap and bundle analyzer from Plans
into their own top-level "Isomorphism" section. The roadmap is the
default page at /isomorphism/, bundle analyzer at /isomorphism/bundle-analyzer.

Plans section retains reader macros and SX-Activity.

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

sx/sxc/pages/docs.sx

@@ -387,6 +387,49 @@
         :bootstrapper-source bootstrapper-source
         :bootstrapped-output bootstrapped-output))))
 
+;; ---------------------------------------------------------------------------
+;; Isomorphism section
+;; ---------------------------------------------------------------------------
+
+(defpage isomorphism-index
+  :path "/isomorphism/"
+  :auth :public
+  :layout (:sx-section
+    :section "Isomorphism"
+    :sub-label "Isomorphism"
+    :sub-href "/isomorphism/"
+    :sub-nav (~section-nav :items isomorphism-nav-items :current "Roadmap")
+    :selected "Roadmap")
+  :content (~plan-isomorphic-content))
+
+(defpage isomorphism-page
+  :path "/isomorphism/<slug>"
+  :auth :public
+  :layout (:sx-section
+    :section "Isomorphism"
+    :sub-label "Isomorphism"
+    :sub-href "/isomorphism/"
+    :sub-nav (~section-nav :items isomorphism-nav-items
+               :current (find-current isomorphism-nav-items slug))
+    :selected (or (find-current isomorphism-nav-items slug) ""))
+  :content (case slug
+    "bundle-analyzer" (~bundle-analyzer-content
+      :pages pages :total-components total-components :total-macros total-macros)
+    :else (~plan-isomorphic-content)))
+
+(defpage bundle-analyzer
+  :path "/isomorphism/bundle-analyzer"
+  :auth :public
+  :layout (:sx-section
+    :section "Isomorphism"
+    :sub-label "Isomorphism"
+    :sub-href "/isomorphism/"
+    :sub-nav (~section-nav :items isomorphism-nav-items :current "Bundle Analyzer")
+    :selected "Bundle Analyzer")
+  :data (bundle-analyzer-data)
+  :content (~bundle-analyzer-content
+    :pages pages :total-components total-components :total-macros total-macros))
+
 ;; ---------------------------------------------------------------------------
 ;; Plans section
 ;; ---------------------------------------------------------------------------
@@ -413,20 +456,6 @@
                :current (find-current plans-nav-items slug))
     :selected (or (find-current plans-nav-items slug) ""))
   :content (case slug
-    "isomorphic-architecture" (~plan-isomorphic-content)
     "reader-macros" (~plan-reader-macros-content)
     "sx-activity" (~plan-sx-activity-content)
     :else (~plans-index-content)))
-
-(defpage bundle-analyzer
-  :path "/plans/bundle-analyzer"
-  :auth :public
-  :layout (:sx-section
-    :section "Plans"
-    :sub-label "Plans"
-    :sub-href "/plans/"
-    :sub-nav (~section-nav :items plans-nav-items :current "Bundle Analyzer")
-    :selected "Bundle Analyzer")
-  :data (bundle-analyzer-data)
-  :content (~bundle-analyzer-content
-    :pages pages :total-components total-components :total-macros total-macros))