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/folding.rs

@@ -1,4 +1,4 @@
-//! Phase 19: LSP folding-range provider.
+//! LSP folding-range provider.
 //!
 //! Drives `folding::folding_ranges` directly. The handler wiring is
 //! shallow — it just calls into this function — so we verify the