Add Semantics geography pages: capabilities, modules, eval-rules

Three new documentation pages under Geography > Semantics:

- Capabilities: abstract evaluation contexts, capability primitives,
  standard capabilities, why not phases
- Modules: the (use) form, what it enables, semantics
- Eval Rules: machine-readable rule set, sx_explain tool, rule structure

Navigation: semantics-nav-items with 3 entries, linked from geography
nav tree after CEK Machine.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sx/nav-tree.sx

@@ -4,7 +4,7 @@
 
 (defcomp ~nav-data/section-nav (&key items current) (<> (map (fn (item) (~shared:layout/nav-link :href (get item "href") :label (get item "label") :is-selected (when (= (get item "label") current) "true") :select-colours "aria-selected:bg-violet-200 aria-selected:text-violet-900")) items)))
 
-(define sx-nav-tree {:href "/sx/" :children (list {:href "/sx/(geography)" :children (list {:href "/sx/(geography.(reactive))" :children reactive-islands-nav-items :label "Reactive Islands"} {:href "/sx/(geography.(hypermedia))" :children (list {:href "/sx/(geography.(hypermedia.(reference)))" :children reference-nav-items :label "Reference"} {:href "/sx/(geography.(hypermedia.(example)))" :children examples-nav-items :label "Examples"}) :label "Hypermedia Lakes"} {:href "/sx/(geography.(scopes))" :summary "The unified primitive beneath provide, collect!, spreads, and islands. Named scope with downward value, upward accumulation, and a dedup flag." :label "Scopes"} {:href "/sx/(geography.(provide))" :summary "Sugar for scope-with-value. Render-time dynamic scope — the substrate beneath spreads, CSSX, and script collection." :label "Provide / Emit!"} {:href "/sx/(geography.(spreads))" :summary "Child-to-parent communication across render boundaries — spread, collect!, reactive-spread, built on scopes." :label "Spreads"} {:href "/sx/(geography.(marshes))" :children marshes-examples-nav-items :summary "Where reactivity and hypermedia interpenetrate — server writes to signals, reactive transforms reshape server content, client state modifies how hypermedia is interpreted." :label "Marshes"} {:href "/sx/(geography.(isomorphism))" :children isomorphism-nav-items :label "Isomorphism"} {:href "/sx/(geography.(cek))" :children cek-nav-items :label "CEK Machine"}) :label "Geography"} {:href "/sx/(language)" :children (list {:href "/sx/(language.(doc))" :children docs-nav-items :label "Docs"} {:href "/sx/(language.(spec))" :children specs-nav-items :label "Specs"} {:href "/sx/(language.(spec.(explore.evaluator)))" :label "Spec Explorer"} {:href "/sx/(language.(bootstrapper))" :children bootstrappers-nav-items :label "Bootstrappers"} {:href "/sx/(language.(test))" :children testing-nav-items :label "Testing"}) :label "Language"} {:href "/sx/(applications)" :children (list {:href "/sx/(applications.(sx-urls))" :label "SX URLs"} {:href "/sx/(applications.(cssx))" :children cssx-nav-items :label "CSSX"} {:href "/sx/(applications.(protocol))" :children protocols-nav-items :label "Protocols"} {:href "/sx/(applications.(sx-pub))" :label "sx-pub"} {:href "/sx/(applications.(reactive-runtime))" :children reactive-runtime-nav-items :label "Reactive Runtime"}) :label "Applications"} {:href "/sx/(tools)" :children tools-nav-items :label "Tools"} {:href "/sx/(etc)" :children (list {:href "/sx/(etc.(essay))" :children essays-nav-items :label "Essays"} {:href "/sx/(etc.(philosophy))" :children philosophy-nav-items :label "Philosophy"} {:href "/sx/(etc.(plan))" :children plans-nav-items :label "Plans"}) :label "Etc"}) :label "sx"})
+(define sx-nav-tree {:href "/sx/" :children (list {:href "/sx/(geography)" :children (list {:href "/sx/(geography.(reactive))" :children reactive-islands-nav-items :label "Reactive Islands"} {:href "/sx/(geography.(hypermedia))" :children (list {:href "/sx/(geography.(hypermedia.(reference)))" :children reference-nav-items :label "Reference"} {:href "/sx/(geography.(hypermedia.(example)))" :children examples-nav-items :label "Examples"}) :label "Hypermedia Lakes"} {:href "/sx/(geography.(scopes))" :summary "The unified primitive beneath provide, collect!, spreads, and islands. Named scope with downward value, upward accumulation, and a dedup flag." :label "Scopes"} {:href "/sx/(geography.(provide))" :summary "Sugar for scope-with-value. Render-time dynamic scope — the substrate beneath spreads, CSSX, and script collection." :label "Provide / Emit!"} {:href "/sx/(geography.(spreads))" :summary "Child-to-parent communication across render boundaries — spread, collect!, reactive-spread, built on scopes." :label "Spreads"} {:href "/sx/(geography.(marshes))" :children marshes-examples-nav-items :summary "Where reactivity and hypermedia interpenetrate — server writes to signals, reactive transforms reshape server content, client state modifies how hypermedia is interpreted." :label "Marshes"} {:href "/sx/(geography.(isomorphism))" :children isomorphism-nav-items :label "Isomorphism"} {:href "/sx/(geography.(cek))" :children cek-nav-items :label "CEK Machine"} {:href "/sx/(geography.(capabilities))" :children semantics-nav-items :label "Semantics"}) :label "Geography"} {:href "/sx/(language)" :children (list {:href "/sx/(language.(doc))" :children docs-nav-items :label "Docs"} {:href "/sx/(language.(spec))" :children specs-nav-items :label "Specs"} {:href "/sx/(language.(spec.(explore.evaluator)))" :label "Spec Explorer"} {:href "/sx/(language.(bootstrapper))" :children bootstrappers-nav-items :label "Bootstrappers"} {:href "/sx/(language.(test))" :children testing-nav-items :label "Testing"}) :label "Language"} {:href "/sx/(applications)" :children (list {:href "/sx/(applications.(sx-urls))" :label "SX URLs"} {:href "/sx/(applications.(cssx))" :children cssx-nav-items :label "CSSX"} {:href "/sx/(applications.(protocol))" :children protocols-nav-items :label "Protocols"} {:href "/sx/(applications.(sx-pub))" :label "sx-pub"} {:href "/sx/(applications.(reactive-runtime))" :children reactive-runtime-nav-items :label "Reactive Runtime"}) :label "Applications"} {:href "/sx/(tools)" :children tools-nav-items :label "Tools"} {:href "/sx/(etc)" :children (list {:href "/sx/(etc.(essay))" :children essays-nav-items :label "Essays"} {:href "/sx/(etc.(philosophy))" :children philosophy-nav-items :label "Philosophy"} {:href "/sx/(etc.(plan))" :children plans-nav-items :label "Plans"}) :label "Etc"}) :label "sx"})
 
 (define has-descendant-href? (fn (node path) (let ((children (get node "children"))) (when children (some (fn (child) (or (= (get child "href") path) (has-descendant-href? child path))) children)))))