Rename set-type to set-connector-type; help-panel & types-glossary polish.

- Command renamed from `set-type` to `set-connector-type` for
  clarity (the previous name was ambiguous — "type" of what?). No
  legacy alias kept; old scripts that still used `set-type` must be
  migrated. `test/system.essim` and all user/design docs updated.
- Help panel (RenderHelpPanel) now wraps in borderRounded with a
  centred bold title, so it is visually distinct from the main
  content on every screen. Width bumped from 30 to 32 to include
  the border.
- Analyze screen's Types tab gains a sibling "type glossary" panel
  (also borderRounded, only visible when the Types tab is focused)
  that explains Power / Suspect Power / Hard floor / Gnd in plain
  language using `paragraph()` for clean word-wrap.

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

tests/test_vpx_transform.cpp

@@ -16,7 +16,7 @@
 namespace {
 
 // Build a Part with `pin_names` pins, attached to a fresh module so prnt
-// chains exist (set-type's validation depends on pins; transforms don't).
+// chains exist (set-connector-type's validation depends on pins; transforms don't).
 Part *make_part(Module *mod, const std::string &part_name,
                 const std::vector<std::string> &pin_names) {
     Part *p = new Part(part_name);