fix(api): point fresh installs at project setup when resolve finds an empty projects table

On a brand-new config dir, model_post_init bootstraps a 'main' default in
config.json but the one-shot CLI path never runs the server-lifespan
reconciliation that would create its database row, so the first read fails
with a bare "Project not found: 'main'" — which reads as a broken install
rather than a missing first-run step. When resolution misses and the
projects table is empty, the 404 now names the setup command.

Follow-up to #974/#985/#987 (which repair the default during project add
but cannot help when the first action is a read). Refs #974.

Signed-off-by: phernandez <paul@basicmachines.co>

src/basic_memory/api/v2/routers/project_router.py

@@ -320,7 +320,20 @@ async def resolve_project_identifier(
     )
 
     if not project:
-        raise HTTPException(status_code=404, detail=f"Project not found: '{data.identifier}'")
+        detail = f"Project not found: '{data.identifier}'"
+        # Trigger: resolution missed and the projects table is empty.
+        # Why: a fresh install bootstraps config.json's default project before any
+        #      reconciliation has created database rows (the one-shot CLI never runs
+        #      the server lifespan), so the first read fails on the configured
+        #      default and the bare not-found message reads as a broken install
+        #      rather than a missing first-run step (#974 follow-up).
+        # Outcome: the error names the setup command instead.
+        if not await project_repository.find_all(limit=1, use_load_options=False):
+            detail = (
+                f"{detail}. No projects are set up yet — run "
+                "'basic-memory project add <name> <path>' to create one."
+            )
+        raise HTTPException(status_code=404, detail=detail)
 
     return ProjectResolveResponse(
         external_id=project.external_id,