Launcher polish: monogram reveal-on-failure + app placeholder on every icon surface (v0.163.1)

(A) The launcher monogram bled through every transparent white logo — it rendered
unconditionally under the img. Now hidden by default (.launch-mono display:none),
revealed only when the img chain fails (onerror adds .launch-tile--noimg).

(B) The /static/app-placeholder.svg default reached only app_list_row. The four
other sanctioned app-logo onerror chains now match the canonical SVG->PNG->placeholder
grammar: backups_apps (aligned row), stacks (infra->infra-logo else placeholder),
app_info hero (screenshots still vanish), deploy (keeps .LogoURL/.LogoPNGURL).

Template/CSS only; no handler/funcmap change. 5 tests + 2 red-proofs.

controller/internal/web/templates/launcher.html

@@ -14,7 +14,7 @@
         <span class="launch-tile" style="background: {{tileColor .Slug .BrandColor}}">
             <span class="launch-mono">{{initial .DisplayName}}</span>
             <img class="launch-logo" src="{{logoURL .Slug}}" alt=""
-                 onerror="if(!this.dataset.step){this.dataset.step='1';this.src='{{logoPNGURL .Slug}}';}else{this.onerror=null;this.style.display='none';}">
+                 onerror="if(!this.dataset.step){this.dataset.step='1';this.src='{{logoPNGURL .Slug}}';}else{this.onerror=null;this.style.display='none';this.parentElement.classList.add('launch-tile--noimg');}">
         </span>
         <span class="launch-name">{{.DisplayName}}</span>
         {{if ne (stateStr .State) "running"}}<span class="tag tag-{{stateColor .State}}"><span class="dot"></span>{{stateLabel .State}}</span>{{end}}
@@ -24,7 +24,7 @@
         <span class="launch-tile launch-tile--off" style="background: {{tileColor .Slug .BrandColor}}">
             <span class="launch-mono">{{initial .DisplayName}}</span>
             <img class="launch-logo" src="{{logoURL .Slug}}" alt=""
-                 onerror="if(!this.dataset.step){this.dataset.step='1';this.src='{{logoPNGURL .Slug}}';}else{this.onerror=null;this.style.display='none';}">
+                 onerror="if(!this.dataset.step){this.dataset.step='1';this.src='{{logoPNGURL .Slug}}';}else{this.onerror=null;this.style.display='none';this.parentElement.classList.add('launch-tile--noimg');}">
         </span>
         <span class="launch-name">{{.DisplayName}}</span>
         <span class="tag tag-{{stateColor .State}}"><span class="dot"></span>{{stateLabel .State}}</span>