Added migrate to shoehorn script

migrate-to-shoehorn/SKILL.md

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+---
+name: migrate-to-shoehorn
+description: Migrate test files from `as` type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace `as` in tests, or needs partial test data.
+---
+
+# Migrate to Shoehorn
+
+## Why shoehorn?
+
+`shoehorn` lets you pass partial data in tests while keeping TypeScript happy. It replaces `as` assertions with type-safe alternatives.
+
+Problems with `as` in tests:
+
+- Trained not to use it
+- Must manually specify target type
+- Double-as (`as unknown as Type`) for intentionally wrong data
+
+## Install
+
+```bash
+npm i @total-typescript/shoehorn
+```
+
+## Migration patterns
+
+### Large objects with few needed properties
+
+Before:
+
+```ts
+type Request = {
+  body: { id: string };
+  headers: Record<string, string>;
+  cookies: Record<string, string>;
+  // ...20 more properties
+};
+
+it("gets user by id", () => {
+  // Only care about body.id but must fake entire Request
+  getUser({
+    body: { id: "123" },
+    headers: {},
+    cookies: {},
+    // ...fake all 20 properties
+  });
+});
+```
+
+After:
+
+```ts
+import { fromPartial } from "@total-typescript/shoehorn";
+
+it("gets user by id", () => {
+  getUser(
+    fromPartial({
+      body: { id: "123" },
+    }),
+  );
+});
+```
+
+### `as Type` → `fromPartial()`
+
+Before:
+
+```ts
+getUser({ body: { id: "123" } } as Request);
+```
+
+After:
+
+```ts
+import { fromPartial } from "@total-typescript/shoehorn";
+
+getUser(fromPartial({ body: { id: "123" } }));
+```
+
+### `as unknown as Type` → `fromAny()`
+
+Before:
+
+```ts
+getUser({ body: { id: 123 } } as unknown as Request); // wrong type on purpose
+```
+
+After:
+
+```ts
+import { fromAny } from "@total-typescript/shoehorn";
+
+getUser(fromAny({ body: { id: 123 } }));
+```
+
+## When to use each
+
+| Function        | Use case                                           |
+| --------------- | -------------------------------------------------- |
+| `fromPartial()` | Pass partial data that still type-checks           |
+| `fromAny()`     | Pass intentionally wrong data (keeps autocomplete) |
+| `fromExact()`   | Force full object (swap with fromPartial later)    |
+
+## Workflow
+
+- [ ] Install package
+- [ ] Find test files with `as` assertions: `grep -r " as [A-Z]" --include="*.test.ts" --include="*.spec.ts"`
+- [ ] Replace `as Type` with `fromPartial()`
+- [ ] Replace `as unknown as Type` with `fromAny()`
+- [ ] Add imports from `@total-typescript/shoehorn`
+- [ ] Run type check to verify