fix: html-router modals and add insta snapshot tests.

Avoid nested forms in the scratchpad editor, centralize modal lifecycle in modal.js, return HTMX partials from archive, and add template compile plus layout snapshots.

html-router/tests/snapshots/search_main.snap

@@ -0,0 +1,46 @@
+---
+source: html-router/tests/router_integration.rs
+expression: main
+---
+
+        
+<div id="search_pane" class="flex justify-center grow mt-2 sm:mt-4">
+  <div class="container">
+    <section class="mb-4">
+      <div class="nb-panel p-3 flex items-center justify-between">
+        
+  <div>
+    <h1 class="text-xl font-extrabold tracking-tight">Search</h1>
+    <div class="text-xs opacity-70">Find document snippets and knowledge entities</div>
+  </div>
+  <form hx-get="/search" hx-target="#search_pane" hx-swap="outerHTML" hx-push-url="true"
+    class="flex items-center gap-1">
+    
+    <button type="submit" name="view" value="all"
+      class="nb-btn btn-sm nb-cta">
+      All
+    </button>
+    <button type="submit" name="view" value="chunks"
+      class="nb-btn btn-sm btn-ghost">
+      Chunks
+    </button>
+    <button type="submit" name="view" value="entities"
+      class="nb-btn btn-sm btn-ghost">
+      Entities
+    </button>
+  </form>
+
+      </div>
+    </section>
+    
+  
+<div class="nb-panel p-5 text-center">
+  <p class="text-lg font-semibold">Enter a term above to search your knowledge base.</p>
+  <p class="text-sm opacity-70">Results will appear here.</p>
+</div>
+
+
+  </div>
+</div>
+
+        <div class="p32 min-h-[10px]"></div>