Add component name formatters and grid-link navigation

Templates section:
- Define JS formatter functions per template (e.g. resistor, capacitor)
- First non-null result from any formatter is used as display name
- Live preview in template editor against first component
- Display names applied in component list, detail view, and inventory rows

Grid navigation:
- Grid-type inventory entries in component detail view show a '⊞' button
  to navigate directly to that grid's viewer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/index.html

@@ -15,6 +15,7 @@
 			<button class="nav-btn" data-section="inventory">Inventory</button>
 			<button class="nav-btn" data-section="fields">Fields</button>
 			<button class="nav-btn" data-section="grids">Grids</button>
+			<button class="nav-btn" data-section="templates">Templates</button>
 		</nav>
 	</header>
 	<main id="main"></main>