supabase / mcp / 40561563459

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fix(mcp-server-supabase): use POSIX path resolution for edge function filenames (#393)

## What kind of change does this PR introduce?

Bug fix

## What is the current behavior?

`normalizeFilename` in
`packages/mcp-server-supabase/src/edge-function.ts` imports `resolve`
from `node:path`, which is platform-dispatched. The function only ever
sees POSIX-shaped strings: `getPathPrefix` returns the hardcoded
`/tmp/user_fn_<id>/`, and Deno's local dev server always emits
forward-slash paths.

On Windows the platform-default `node:path` rewrites the leading slash
to a drive letter and the slashes to backslashes, so:

- the absolute-path merge `resolve('/tmp/user_fn_…/',
'/tmp/user_fn_…/source/index.ts')` produces
`C:\tmp\user_fn_…\source\index.ts` (dropping `/tmp/…` entirely because
the second arg is absolute and platform-default),
- the downstream `value.startsWith(pathPrefix)` strip never matches, and
- the second `withoutPrefix(…, 'source/')` strip actually fires on a
Windows path and returns the truncated value.

A developer running the MCP server locally on Windows therefore sees
`get_edge_function` and `list_edge_functions` return `entrypoint_path`
and `files[].name` as `C:\tmp\user_fn_<id>\index.ts` rather than
`index.ts`. The bug is invisible to the hosted server (Linux) and to CI
(Linux-only).

The five failing unit tests in the issue's reproduction all show the
same root cause:
- `edge-function.test.ts > normalizeFilename > handles deno 1 paths`
- `edge-function.test.ts > normalizeFilename > handles deno 2 paths`
- `edge-function.test.ts > normalizeFilename > doesn't interfere with
nested directories`
- `server.test.ts > tools > list edge functions`
- `server.test.ts > tools > get edge function`

## What is the new behavior?

Switch the single import to `node:path/posix`:

```ts
-import { resolve } from 'node:path';
+import { resolve } from 'node:path/posix';
```

`getPathPrefix` still returns `/tmp/user_fn_<id>/` and the
`withoutPrefix` strip sti... (continued)

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