Rename phase-numbered tests and drop SPEC pointer from stub messages

Rename the four commands_list_includes_phaseNN_entries tests after the
command namespace they cover (wiki, link health, export, diary), and
strip the "see SPEC §13.1" pointer from the not-yet-implemented runtime
notifications.

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

crates/nuwiki-lsp/tests/html_export.rs

@@ -474,7 +474,7 @@ fn write_rss_emits_valid_xml_with_entries() {
 // ===== COMMANDS list completeness =====
 
 #[test]
-fn commands_list_includes_phase17_entries() {
+fn commands_list_includes_export_entries() {
     let names: Vec<&str> = nuwiki_lsp::commands::COMMANDS.to_vec();
     for name in [
         "nuwiki.export.currentToHtml",