Add live bundle analyzer page to sx-docs

Demonstrates Phase 1 dep analysis in action: computes per-page component
bundles for all sx-docs pages using the deps.sx transitive closure
algorithm, showing needed vs total components with visual progress bars.

- New page at /plans/bundle-analyzer with Python data helper
- New components: ~bundle-analyzer-content, ~analyzer-stat, ~analyzer-row
- Linked from Phase 1 section and Plans nav
- Added sx/sx/ to tailwind content paths

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

sx/sx/nav-data.sx

@@ -105,6 +105,8 @@
 (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"