test(rag): switch to workspace project explicitly before configuring RAG

Per Tier 1 addendum 3 (the real defect): tests hotpatch individual state
fields via set_value instead of calling the proper project-switch
flow. The session-scoped subprocess may be on a stale project from a
prior test (e.g. test_context_sim_live switches to
temp_livecontextsim.toml and never switches back). The RAG engine uses
active_project_root (derived from active_project_path) as its base_dir,
NOT ui_files_base_dir. So hotpatching files/rag_enabled via set_value
while active_project_path is stale leaves the RAG engine looking at a
dead dir.

Fix: switch to the workspace project explicitly at the start of the
test (like a user would) using client.push_event('custom_callback',
...) + client.wait_for_project_switch(...). The path must be absolute
because the subprocess's CWD is the workspace, so a relative path
like 'tests/artifacts/.../manualslop.toml' would resolve to the wrong
dir from the subprocess's CWD.

Verified: the switch fires successfully (no WARNING printed). But the
RAG search still returns 0 chunks — the index_file rebuild is not
adding the files. The exact cause is still under investigation.

This is the proper fix per Tier 1 (NOT "delete stale files" which
treats the symptom). The sim tests' teardown() also needs a switch-back
to the workspace project (separate track).

tests/test_rag_phase4_final_verify.py

@@ -17,6 +17,25 @@ def test_phase4_final_verify(live_gui, live_gui_workspace):
  client = api_hook_client.ApiHookClient()
  assert client.wait_for_server(timeout=15), "Hook server did not start"
 
+ # PROPER PROJECT CONTEXT (per Tier 1 addendum 3):
+ # The session-scoped subprocess may be on a stale project from a prior
+ # test (e.g. test_context_sim_live switches to temp_livecontextsim.toml
+ # and never switches back). The RAG engine uses active_project_root
+ # (derived from active_project_path) as its base_dir, NOT
+ # ui_files_base_dir. So hotpatching files/rag_enabled via set_value
+ # while active_project_path is stale leaves the RAG engine looking at
+ # a dead dir. Switch to the workspace project explicitly (like a user
+ # would) before configuring files and RAG.
+ # Must use absolute path — the subprocess's CWD is the workspace, so a
+ # relative path like 'tests/artifacts/.../manualslop.toml' resolves to
+ # the wrong dir from the subprocess's CWD.
+ workspace_toml = str((Path(live_gui_workspace) / "manualslop.toml").resolve())
+ if Path(workspace_toml).exists():
+  client.push_event("custom_callback", {"callback": "_switch_project", "args": [workspace_toml]})
+  switch_status = client.wait_for_project_switch(expected_path=workspace_toml, timeout=30.0)
+  if switch_status.get("error"):
+   print(f"[VERIFY] WARNING: project switch error: {switch_status.get('error')}")
+
  # Use a unique collection name per test invocation. The RAG engine
  # stores its chromadb collection at
  # <base_dir>/.slop_cache/chroma_<collection_name>. The live_gui