feat(plugins): split plugin code by runtime

Keep the entry point focused on contribution wiring so client UI and daemon handlers can use their own runtime APIs safely. Surface compilation failures and lifecycle transitions in the retained plugin log tail.

plugin-examples/linear/issues.shared.ts

@@ -0,0 +1,31 @@
+import { defineAttachmentSource, defineRpc } from "@paseo/plugin";
+import { z } from "zod";
+
+const SearchPayloadSchema = z.object({
+  items: z.array(
+    z.object({
+      id: z.string(),
+      identifier: z.string(),
+      title: z.string(),
+      subtitle: z.string().optional(),
+      url: z.string().url(),
+      text: z.string(),
+      resourceType: z.string(),
+    }),
+  ),
+});
+
+export const searchIssuesRpc = defineRpc({
+  name: "issues.search",
+  input: z.object({ query: z.string() }),
+  output: SearchPayloadSchema,
+});
+
+export const issueAttachments = defineAttachmentSource({
+  id: "issues",
+  title: "Linear issue",
+  icon: "CircleDot",
+  pickerTitle: "Attach Linear issue",
+  searchPlaceholder: "Search by identifier or title",
+  search: searchIssuesRpc,
+});