Revert trailing slash removal from project list client path

The trailing slash on /v2/projects/ is required because the FastAPI
route is defined as @router.get("/"). Removing it caused 307 redirects
that broke call_get (which doesn't follow redirects), failing all
project management tests in CI.

The cloud proxy's defense-in-depth filtering already handles both
slash variants via rstrip("/"), so the trailing slash was never
causing a filtering bypass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Joe P <joe@basicmemory.com>

Author: jope-bm

src/basic_memory/mcp/clients/project.py

@@ -55,7 +55,7 @@ async def list_projects(self) -> ProjectList:
         """
         response = await call_get(
             self.http_client,
-            "/v2/projects",
+            "/v2/projects/",
         )
         return ProjectList.model_validate(response.json())