Add unmanaged skill provenance to agent skills

Expose adapter-discovered user-installed skills with provenance metadata, share persistent skill snapshot classification across local adapters, and render unmanaged skills as a read-only section in the agent skills UI.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/lib/agent-skills-state.ts

@@ -1,3 +1,5 @@
+import type { AgentSkillEntry } from "@paperclipai/shared";
+
 export interface AgentSkillDraftState {
   draft: string[];
   lastSaved: string[];
@@ -27,3 +29,12 @@ export function applyAgentSkillSnapshot(
     shouldSkipAutosave: shouldReplaceDraft,
   };
 }
+
+export function isReadOnlyUnmanagedSkillEntry(
+  entry: AgentSkillEntry,
+  companySkillKeys: Set<string>,
+): boolean {
+  if (companySkillKeys.has(entry.key)) return false;
+  if (entry.origin === "user_installed" || entry.origin === "external_unknown") return true;
+  return entry.managed === false && entry.state === "external";
+}