feat(admin): restore org Agent role/skill management and fix 404 after project create

- explorer POST /projects now returns {id,name} matching the SPA contract
  (previously returned ProjectOnboardingResult.projectId, so res.id was
  undefined and the redirect to /projects/undefined 404'd)
- add OrganizationAgentConfiguration.listRoles/listSkills + AgentRoleRow/
  AgentSkillRow exports; upsertRole now returns the full row
- new agentConfigRoutes: GET/PUT /agent-roles, PUT /agent-roles/:id/skills,
  GET /agent-skills, GET /agent-models (env-default picker)
- restore admin-web roles page + RoleCard rewired to ADR-0017/0018 backend
  (label, defaultModel, tools whitelist, skill binding, systemPrompt,
  sortOrder, default toggle); add 角色 nav item + roles icon
- skill installation stays out-of-band (CLI/seed) per spec; the surface only
  lists installed skills and binds them to roles

hub/admin-web/src/lib/components/Icon.svelte

@@ -11,14 +11,15 @@
 			| 'projects'
 			| 'provider'
 			| 'feishu'
-		| 'menu'
-		| 'logout'
-		| 'org'
-		| 'chevron'
-		| 'arrow-left'
-		| 'folder'
+			| 'menu'
+			| 'logout'
+			| 'org'
+			| 'chevron'
+			| 'arrow-left'
+			| 'folder'
 			| 'file'
-			| 'check';
+			| 'check'
+			| 'roles';
 		class?: string;
 	} = $props();
 </script>
@@ -103,11 +104,7 @@
 	</svg>
 {:else if name === 'arrow-left'}
 	<svg class={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
-		<path
-			stroke-linecap="round"
-			stroke-linejoin="round"
-			d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18"
-		/>
+		<path stroke-linecap="round" stroke-linejoin="round" d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18" />
 	</svg>
 {:else if name === 'folder'}
 	<svg class={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
@@ -129,4 +126,12 @@
 	<svg class={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
 		<path stroke-linecap="round" stroke-linejoin="round" d="M4.5 12.75l6 6 9-13.5" />
 	</svg>
+{:else if name === 'roles'}
+	<svg class={className} viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75">
+		<path
+			stroke-linecap="round"
+			stroke-linejoin="round"
+			d="M9.813 15.904L9 18.75l-.813-2.846a4.5 4.5 0 00-3.09-3.09L2.25 12l2.847-.813a4.5 4.5 0 003.09-3.09L9 5.25l.813 2.846a4.5 4.5 0 003.09 3.09L15.75 12l-2.847.813a4.5 4.5 0 00-3.09 3.09zM18.259 8.715L18 9.75l-.259-1.035a3.375 3.375 0 00-2.456-2.456L14.25 6l1.035-.259a3.375 3.375 0 002.456-2.456L18 2.25l.259 1.035a3.375 3.375 0 002.456 2.456L21.75 6l-1.035.259a3.375 3.375 0 00-2.456 2.456zM16.894 20.567L16.5 21.75l-.394-1.183a2.25 2.25 0 00-1.423-1.423L13.5 18.75l1.183-.394a2.25 2.25 0 001.423-1.423l.394-1.183.394 1.183a2.25 2.25 0 001.423 1.423l1.183.394-1.183.394a2.25 2.25 0 00-1.423 1.423z"
+		/>
+	</svg>
 {/if}