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>

src/tui/tui.cpp

@@ -100,7 +100,7 @@ void Tui::Run() {
             if (e == Event::Character("c")) { screen_idx = 0;       return true; }
             if (e == Event::Character("p")) { Dispatch("connect");  return true; }
             if (e == Event::Character("s")) { Dispatch("search");   return true; }
-            if (e == Event::Character("t")) { Dispatch("set-type"); return true; }
+            if (e == Event::Character("t")) { Dispatch("set-connector-type"); return true; }
             if (e == Event::Character("e")) { Dispatch("explore");  return true; }
             if (e == Event::Character("n")) { Dispatch("net");      return true; }
             // [a]nalyze is the unified verify + analyze screen (issues +
@@ -121,7 +121,7 @@ void Tui::Run() {
             if (e == Event::TabReverse) { explore_focus_idx = (explore_focus_idx + 5) % 6; return true; }
             return false;
 
-        case 3:  // set-type
+        case 3:  // set-connector-type
             if (e == Event::Escape) { screen_idx = 6; return true; }
             if (e == Event::Tab)        { settype_focus_idx = (settype_focus_idx + 1) % 5; return true; }
             if (e == Event::TabReverse) { settype_focus_idx = (settype_focus_idx + 4) % 5; return true; }