Remove stale phase/spec references from code comments

Strip "Phase N", "SPEC §X.Y", and "v1.x" planning labels from comments
across the Rust crates and editor layers now that those tracking
artifacts are gone. Comments only — no logic, strings, or test names
touched.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugin/nuwiki.vim

@@ -4,7 +4,7 @@
 " their config (lazy.nvim does this automatically through `opts`). On Vim
 " we start the LSP client when a vimwiki buffer is loaded.
 "
-" Per SPEC §6.2 / §6.3 this file contains wiring only — all logic lives in
+" This file contains wiring only — all logic lives in
 " the Rust language server.
 
 if exists('g:loaded_nuwiki')