feat(adapters): external adapter plugin system with dynamic UI parser

- Plugin loader: install/reload/remove/reinstall external adapters
  from npm packages or local directories
- Plugin store persisted at ~/.paperclip/adapter-plugins.json
- Self-healing UI parser resolution with version caching
- UI: Adapter Manager page, dynamic loader, display registry
  with humanized names for unknown adapter types
- Dev watch: exclude adapter-plugins dir from tsx watcher
  to prevent mid-request server restarts during reinstall
- All consumer fallbacks use getAdapterLabel() for consistent display
- AdapterTypeDropdown uses controlled open state for proper close behavior
- Remove hermes-local from built-in UI (externalized to plugin)
- Add docs for external adapters and UI parser contract

packages/shared/src/validators/agent.ts

@@ -1,11 +1,11 @@
 import { z } from "zod";
 import {
-  AGENT_ADAPTER_TYPES,
   AGENT_ICON_NAMES,
   AGENT_ROLES,
   AGENT_STATUSES,
   INBOX_MINE_ISSUE_STATUS_FILTER,
 } from "../constants.js";
+import { agentAdapterTypeSchema } from "../adapter-type.js";
 import { envConfigSchema } from "./secret.js";
 
 export const agentPermissionsSchema = z.object({
@@ -52,7 +52,7 @@ export const createAgentSchema = z.object({
   reportsTo: z.string().uuid().optional().nullable(),
   capabilities: z.string().optional().nullable(),
   desiredSkills: z.array(z.string().min(1)).optional(),
-  adapterType: z.enum(AGENT_ADAPTER_TYPES).optional().default("process"),
+  adapterType: agentAdapterTypeSchema,
   adapterConfig: adapterConfigSchema.optional().default({}),
   runtimeConfig: z.record(z.unknown()).optional().default({}),
   budgetMonthlyCents: z.number().int().nonnegative().optional().default(0),