test(router): pin a catch-all tail segment ending in } as literal (#193)

<!-- claude-projects-attribution: {"github_login":"dinwwwh"} -->
_Requested by **dinwwwh** · [project
thread](https://claude.ai/code/project/chan_01UcKMz91tMarPV1kWLVgLYE?thread=cmsg_01UcKMz91tMarPV1kWLVgLYE6swgSUM9SyULmBVdRjY2t7)_

## What

This is a test-only change. The literal-text test in `router.test.ts`
now adds `/f/{+p}/id}` and checks two requests:

- `/f/1/id}` matches it, with `{ p: '1' }`.
- `/f/1/id` matches nothing.

## Why

Since #186, the tree build calls `toSegment` only for parts that start
with `{`. A catch-all's tail segments still go through `toSegment`
whatever they start with, and so do `parse`'s callers
(`createPrefixMatcher` and the two-catch-all check in `add`). Mutation
testing found that dropping the leading-`{` half of `toSegment`'s param
check failed no test, even with the 73 tests now on main. With that
mutant, `id}` becomes a param named `d`, so `/f/1/id` matches. The new
assertions catch it.

## Checks

- All 73 router tests pass, and `pnpm check` passes.
- With that mutant applied, the test fails.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01VVaw7Sutbw6xMTMyDFeNfw)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: dinwwwh

packages/router/tests/router.test.ts

@@ -96,6 +96,7 @@ describe('Router', () => {
         '/{id',
         '/id}',
         '/id}/{x}',
+        '/f/{+p}/id}',
       )
 
       for (const path of [
@@ -117,6 +118,8 @@ describe('Router', () => {
       expect(router.match('GET', '/anything')).toBeUndefined()
       expect(router.match('GET', '/x')).toBeUndefined()
       expect(router.match('GET', '/itemsfoo')).toBeUndefined()
+      expect(router.match('GET', '/f/1/id}')).toEqual({ data: '/f/{+p}/id}', params: { p: '1' } })
+      expect(router.match('GET', '/f/1/id')).toBeUndefined()
 
       // only a whole-segment `{name}` is a param
       expect(router.match('GET', '/a/%7Bid%7D.json')).toEqual({