chore(ruff) ruff v0.12.1 aggressive fixes

uv run ruff check --select ALL . --fix --unsafe-fixes --preview --show-fixes; uv run ruff format .

Fixed 2 errors:
- src/tmuxp/workspace/finders.py:
    2 × PLC1802 (len-test)

Found 1112 errors (2 fixed, 1110 remaining)

Author: tony

src/tmuxp/workspace/finders.py

@@ -218,9 +218,9 @@ def find_workspace_file(
                     "Use file names e.g. myproject.json, coolproject.yaml. "
                     "You can load them by filename.",
                 )
-            elif not len(candidates):
+            elif not candidates:
                 file_error = "No tmuxp files found in directory"
-        if len(candidates):
+        if candidates:
             workspace_file = candidates[0]
     elif not exists(workspace_file):
         file_error = "file not found"