refactor(stdlib): de-abbreviate namespaces (Mem/Sys/Net/Collide)

Expand the abbreviated public namespaces to full words, part of the
language-wide de-abbreviation pass:
  Mem -> Memory, Sys -> System, Net -> Network, Collide -> Collision

Math stays (universally accepted, like int/bool). Renames the dispatch
strings, LSP signatures, docs (dirs, files, frontmatter), and the
inventory manifest; behavior is byte-identical (the bare rt_ targets are
unchanged). Reseeded; C-free bootstrap fixpoint holds; all suites green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/language/network/network-apply.md

@@ -0,0 +1,14 @@
+---
+id: network-apply
+name: Network.apply
+category: network
+kind: namespace-method
+tokens: Network.apply
+sig: Network.apply(entity, buf) -> int
+tip: Apply serialized state to an entity.
+order: 3
+ns: Network
+member: apply
+---
+
+Reads synced fields from <code>buf</code> into <code>entity</code> — the inverse of <code>Network.serialize</code>.