chore: consolidate test files into __tests__/ dirs and clean stray engine artifacts

- Move all co-located *.test.* files into sibling __tests__/ directories so the
  layout is consistent across packages (159 renames + content-rewrite moves).
  Updates relative imports, vi.mock specifiers, and __dirname/import.meta.url
  path resolutions where tests read fixtures from disk.
- Drop tracked tsc-emit alongside engine .ts sources (auth-storage/logger/
  skill-resolver/context-limit-detector/pi.{js,d.ts,*.map}). These were
  accidentally committed in a merge and the stale pi.js was masking a real
  test-mock vs source mismatch (tests imported "../pi.js" and vite preferred
  the stale build over pi.ts).
- Add packages/engine/.gitignore to block future src/*.{js,d.ts,map}.
- Refactor plugin pi-module seams (openclaw/paperclip/hermes) to ESM-import
  createFnAgent / promptWithFallback / describeModel from @fusion/engine
  instead of require()-ing packages/engine/src/pi.js. Adds @fusion/engine to
  the two plugin package.jsons that were missing it; exports describeModel
  from the engine public API.
- Fix engine test mocks now that they run against current pi.ts: add
  ModelRegistry.create static to mocks in pi.test.ts and pi-create-fn-agent
  .test.ts; switch three boundary-result toEqual assertions to toMatchObject
  so the new content/isError fields don't trip exact-match comparison.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plugins/fusion-plugin-paperclip-runtime/src/pi-module.ts

@@ -2,25 +2,15 @@
  * Pi Module Seam
  *
  * Provides a mockable import path for pi functions used by the PaperclipRuntimeAdapter.
- * This module creates a seam that Vitest can intercept via vi.mock().
- *
- * ## Why a Seam Module?
- *
- * The pi functions (createFnAgent, promptWithFallback, describeModel) are defined
- * in packages/engine/src/pi.ts but are not exported from the @fusion/engine public API.
- * This seam provides a controlled import path that can be mocked in tests.
- *
- * ## Mocking in Tests
- *
- * Vitest can mock this module using:
- * ```typescript
- * vi.mock("../pi-module.js", () => ({
- *   createFnAgent: mockCreateFnAgent,
- *   promptWithFallback: mockPromptWithFallback,
- *   describeModel: mockDescribeModel,
- * }));
- * ```
+ * Tests intercept this module via `vi.mock("../pi-module.js", ...)`. The runtime
+ * implementations come from @fusion/engine; the local types provide a loose
+ * surface so the adapter doesn't have to depend on @fusion/engine's full types.
  */
+import {
+  createFnAgent as _createFnAgent,
+  promptWithFallback as _promptWithFallback,
+  describeModel as _describeModel,
+} from "@fusion/engine";
 
 // ── Type Declarations ─────────────────────────────────────────────────────────
 
@@ -55,24 +45,19 @@ export interface PiAgentOptions {
   skills?: string[];
 }
 
-// ── Module Export (runtime resolution) ────────────────────────────────────────
-
-// Use CommonJS require at runtime, which Vitest can mock when using
-// vi.mock() with a factory function. The key is that Vitest hoists vi.mock
-// calls before module evaluation, so the mock is active when require() runs.
-//
-// eslint-disable-next-line @typescript-eslint/no-require-imports
-const _piModule = require("../../../packages/engine/src/pi.js") as {
-  createFnAgent: (options: PiAgentOptions) => Promise<PiAgentResult>;
-  promptWithFallback: (session: PiAgentSession, prompt: string, options?: unknown) => Promise<void>;
-  describeModel: (session: PiAgentSession) => string;
-};
+// ── Module Exports ────────────────────────────────────────────────────────────
 
 /** Create a new agent session using the pi backend */
-export const createFnAgent = _piModule.createFnAgent;
+export const createFnAgent = _createFnAgent as unknown as (
+  options: PiAgentOptions,
+) => Promise<PiAgentResult>;
 
 /** Prompt the session with automatic retry and fallback */
-export const promptWithFallback = _piModule.promptWithFallback;
+export const promptWithFallback = _promptWithFallback as unknown as (
+  session: PiAgentSession,
+  prompt: string,
+  options?: unknown,
+) => Promise<void>;
 
 /** Get a human-readable model description from a session */
-export const describeModel = _piModule.describeModel;
+export const describeModel = _describeModel as unknown as (session: PiAgentSession) => string;