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>

server/src/__tests__/agent-skill-contract.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import {
+  agentSkillEntrySchema,
+  agentSkillSnapshotSchema,
+} from "@paperclipai/shared/validators/adapter-skills";
+
+describe("agent skill contract", () => {
+  it("accepts optional provenance metadata on skill entries", () => {
+    expect(agentSkillEntrySchema.parse({
+      key: "crack-python",
+      runtimeName: "crack-python",
+      desired: false,
+      managed: false,
+      state: "external",
+      origin: "user_installed",
+      originLabel: "User-installed",
+      locationLabel: "~/.claude/skills",
+      readOnly: true,
+      detail: "Installed outside Paperclip management.",
+    })).toMatchObject({
+      origin: "user_installed",
+      locationLabel: "~/.claude/skills",
+      readOnly: true,
+    });
+  });
+
+  it("remains backward compatible with snapshots that omit provenance metadata", () => {
+    expect(agentSkillSnapshotSchema.parse({
+      adapterType: "claude_local",
+      supported: true,
+      mode: "ephemeral",
+      desiredSkills: [],
+      entries: [{
+        key: "paperclipai/paperclip/paperclip",
+        runtimeName: "paperclip",
+        desired: true,
+        managed: true,
+        state: "configured",
+      }],
+      warnings: [],
+    })).toMatchObject({
+      adapterType: "claude_local",
+      entries: [{
+        key: "paperclipai/paperclip/paperclip",
+        state: "configured",
+      }],
+    });
+  });
+});