Document regex code navigation workflow

docs/modernization/build-inventory.md

@@ -109,6 +109,10 @@ Known local toolchain state:
   `python scripts/dev/clangd_nav.py self-test`, also registered as
   `panopainter_clangd_nav_regex_self_test`, so regex filter behavior can be
   validated without clangd or a compile database.
+  Use the repo skill `panopainter-code-navigation` before broad text searches
+  when a C++ refactor needs symbol-family lookup, generated-style names,
+  signatures, override groups, or platform/backend path slices. Keep `rg` for
+  docs, build files, string literals, comments, and exact non-symbol text.
   Reference lookup is guarded because a one-shot clangd process may not have a
   complete project index: pass `--background-index` for broader best-effort
   results or `--allow-incomplete-references` for explicitly