fix(config-settings,docs): address final whole-branch review findings

Bundled fix wave for six findings from the sub-category-granularity
whole-branch review:

- config-settings: reset in_subcat on Tab/Shift-Tab so up/down keep
  routing to cur_row instead of freezing on the Sponge/Paths pages
  after a drill-down
- verify-manual: _parsed_components() now delegates to
  generate_component_registry.collect_components() instead of a
  lossy dict.update() merge, closing a taxonomy-check blind spot on
  identity collisions
- verify-manual: add test_committed_registry_matches_headers to
  catch the committed registry drifting from current # COMPONENT
  headers
- build-docs workflow: trigger on conf.d/** and config.fish edits,
  not just functions/**
- __config_settings_draw_subcat: show (Universal)/(Session) in the
  drill-down title so the persistence scope is visible before toggling
- __config_settings_draw / config-settings: mention the Enter
  sub-category drill-down in the on-screen hint and --help text
- generate_component_registry: send the "wrote ..." progress line to
  stderr so it no longer corrupts --concat's stdout output

.github/workflows/build-docs.yml

@@ -11,6 +11,8 @@ on:
       - "docs/verify-manual.py"
       - "docs/site/**"
       - "functions/**"
+      - "conf.d/**"
+      - "config.fish"
   workflow_dispatch:
 
 jobs: