Add live self-hosting bootstrapper page to bootstrappers section

- Update plan page with completion status and results
- Add ~bootstrapper-self-hosting-content component with live G0/G1 verification
- Add _self_hosting_data() helper: loads py.sx, runs it, diffs against G0
- Add "Self-Hosting (py.sx)" to bootstrappers nav and index table
- Wire /bootstrappers/self-hosting route

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

sx/sx/nav-data.sx

@@ -160,7 +160,7 @@
   (dict :label "Theorem Prover" :href "/plans/theorem-prover"
         :summary "prove.sx — constraint solver and property prover for SX primitives, written in SX.")
   (dict :label "Self-Hosting Bootstrapper" :href "/plans/self-hosting-bootstrapper"
-        :summary "py.sx — an SX-to-Python translator written in SX. The bootstrapper bootstraps itself.")
+        :summary "py.sx — an SX-to-Python translator written in SX. Complete: G0 == G1, 128/128 defines match.")
   (dict :label "JS Bootstrapper" :href "/plans/js-bootstrapper"
         :summary "js.sx — SX-to-JavaScript translator + ahead-of-time component compiler. Zero-runtime static sites.")
   (dict :label "SX-Activity" :href "/plans/sx-activity"
@@ -197,7 +197,8 @@
 (define bootstrappers-nav-items (list
   (dict :label "Overview" :href "/bootstrappers/")
   (dict :label "JavaScript" :href "/bootstrappers/javascript")
-  (dict :label "Python" :href "/bootstrappers/python")))
+  (dict :label "Python" :href "/bootstrappers/python")
+  (dict :label "Self-Hosting (py.sx)" :href "/bootstrappers/self-hosting")))
 
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