Add Philosophy section with Wittgenstein, Dennett, and S-Existentialism essays

New top-level Philosophy section in sx-docs. Moved SX Manifesto and Strange
Loops from Essays, added three new essays: SX and Wittgenstein (language games,
limits of language, fly-bottles), SX and Dennett (real patterns, multiple drafts,
intentional stance), and S-Existentialism (existence precedes essence, bad faith,
the absurd). Updated all cross-references and navigation.

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

sx/sxc/pages/docs.sx

@@ -274,10 +274,8 @@
     "on-demand-css" (~essay-on-demand-css)
     "client-reactivity" (~essay-client-reactivity)
     "sx-native" (~essay-sx-native)
-    "sx-manifesto" (~essay-sx-manifesto)
     "tail-call-optimization" (~essay-tail-call-optimization)
     "continuations" (~essay-continuations)
-    "godel-escher-bach" (~essay-godel-escher-bach)
     "reflexive-web" (~essay-reflexive-web)
     "server-architecture" (~essay-server-architecture)
     "separation-of-concerns" (~essay-separation-of-concerns)
@@ -286,6 +284,39 @@
     "zero-tooling" (~essay-zero-tooling)
     :else (~essays-index-content)))
 
+;; ---------------------------------------------------------------------------
+;; Philosophy section
+;; ---------------------------------------------------------------------------
+
+(defpage philosophy-index
+  :path "/philosophy/"
+  :auth :public
+  :layout (:sx-section
+    :section "Philosophy"
+    :sub-label "Philosophy"
+    :sub-href "/philosophy/"
+    :sub-nav (~section-nav :items philosophy-nav-items :current "")
+    :selected "")
+  :content (~philosophy-index-content))
+
+(defpage philosophy-page
+  :path "/philosophy/<slug>"
+  :auth :public
+  :layout (:sx-section
+    :section "Philosophy"
+    :sub-label "Philosophy"
+    :sub-href "/philosophy/"
+    :sub-nav (~section-nav :items philosophy-nav-items
+               :current (find-current philosophy-nav-items slug))
+    :selected (or (find-current philosophy-nav-items slug) ""))
+  :content (case slug
+    "sx-manifesto" (~essay-sx-manifesto)
+    "godel-escher-bach" (~essay-godel-escher-bach)
+    "wittgenstein" (~essay-sx-and-wittgenstein)
+    "dennett" (~essay-sx-and-dennett)
+    "existentialism" (~essay-s-existentialism)
+    :else (~philosophy-index-content)))
+
 ;; ---------------------------------------------------------------------------
 ;; CSSX section
 ;; ---------------------------------------------------------------------------