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/html_export.rs

@@ -1,4 +1,4 @@
-//! Phase 17: HTML export commands.
+//! HTML export commands.
 //!
 //! Drives the pure `export::*` helpers directly. The side-effecting
 //! `export_ops::write_page` / `write_rss` paths get exercised via a