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/sx/layouts.sx

@@ -14,6 +14,7 @@
            (dict :label "Essays" :href "/essays/")
            (dict :label "Specs" :href "/specs/")
            (dict :label "Bootstrappers" :href "/bootstrappers/")
+           (dict :label "Isomorphism" :href "/isomorphism/")
            (dict :label "Plans" :href "/plans/"))))
     (<> (map (lambda (item)
       (~nav-link

sx/sx/nav-data.sx

@@ -102,11 +102,11 @@
   (dict :label "call/cc" :href "/specs/callcc")
   (dict :label "Deps" :href "/specs/deps")))
 
+(define isomorphism-nav-items (list
+  (dict :label "Roadmap" :href "/isomorphism/")
+  (dict :label "Bundle Analyzer" :href "/isomorphism/bundle-analyzer")))
+
 (define plans-nav-items (list
-  (dict :label "Isomorphic Architecture" :href "/plans/isomorphic-architecture"
-        :summary "Making the server/client boundary a sliding window — per-page bundles, smart expansion, SPA routing, client IO, streaming suspense.")
-  (dict :label "Bundle Analyzer" :href "/plans/bundle-analyzer"
-        :summary "Live per-page component dependency analysis — see which components each page needs and the payload savings.")
   (dict :label "Reader Macros" :href "/plans/reader-macros"
         :summary "Extensible parse-time transformations via # dispatch — datum comments, raw strings, and quote shorthand.")
   (dict :label "SX-Activity" :href "/plans/sx-activity"

sx/sx/plans.sx

@@ -625,7 +625,7 @@
         (div :class "flex items-center gap-2 mb-2"
           (span :class "inline-block px-2 py-0.5 rounded text-xs font-bold bg-green-600 text-white uppercase" "Complete")
           (a :href "/specs/deps" :class "text-green-700 underline text-sm font-medium" "View canonical spec: deps.sx")
-          (a :href "/plans/bundle-analyzer" :class "text-green-700 underline text-sm font-medium" "Live bundle analyzer"))
+          (a :href "/isomorphism/bundle-analyzer" :class "text-green-700 underline text-sm font-medium" "Live bundle analyzer"))
         (p :class "text-green-900 font-medium" "What it enables")
         (p :class "text-green-800" "Per-page component bundles instead of sending every definition to every page. Smaller payloads, faster boot, better cache hit rates."))
 
@@ -677,7 +677,7 @@
           (li "15 dedicated tests: scan, transitive closure, circular deps, compute-all, components-needed")
           (li "Bootstrapped output verified on both host targets")
           (li "Full test suite passes with zero regressions")
-          (li (a :href "/plans/bundle-analyzer" :class "text-violet-700 underline" "Live bundle analyzer") " shows real per-page savings on this app"))))
+          (li (a :href "/isomorphism/bundle-analyzer" :class "text-violet-700 underline" "Live bundle analyzer") " shows real per-page savings on this app"))))
 
     ;; -----------------------------------------------------------------------
     ;; Phase 2

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))