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>

crates/nuwiki-lsp/tests/helpers.rs

@@ -1,7 +1,7 @@
 //! Tests for the pure helpers that the LSP backend uses to translate
 //! between `nuwiki-core` ASTs and the LSP wire format. The async
-//! request-handling loop is exercised at integration time in Phase 8+
-//! (navigation), so this file stays focused on conversion correctness.
+//! request-handling loop is exercised at integration time by the
+//! navigation tests, so this file stays focused on conversion correctness.
 
 use nuwiki_core::ast::{
     inline::InlineNode, BlockNode, BlockquoteNode, DocumentNode, ErrorNode, ParagraphNode,