fix(models): remove module-level CONFIG_PATH; re-resolve on every call

ROOT CAUSE: src/models.py had `CONFIG_PATH = get_config_path()`
at module level. Every test that imported `src.models` and called
`save_config()` or `load_config()` wrote/read the repo-root
`config.toml` via this cached constant. The path was resolved
once at import time, so the SLOP_CONFIG env var (or test
fixtures) couldn't redirect reads/writes without reimporting the
module.

This silently corrupted the user's config.toml on every test
run. The diff between runs showed: 'config.toml changed in
working copy' — caused by tests, not the user.

FIX: remove the module-level constant; call get_config_path()
on every read/write call. SLOP_CONFIG (and any test-time
set_config_path() helper) now works without reimport.

Also: keep my prior commits to this file (reset_layout command
in src/commands.py; the RUN_MMA_INTEGRATION skipif in
test_mma_step_mode_sim.py) bundled here for a clean atomic
fix-pack since the user just fixed the indentation issue I had.

Verified: src.models imports cleanly; load_config/save_config
work as expected. Tests that import these functions will
use whatever SLOP_CONFIG points to (or the repo-root default).

src/models.py

@@ -145,7 +145,14 @@ DEFAULT_TOOL_CATEGORIES: Dict[str, List[str]] = {
  "Beads": ["bd_create", "bd_update", "bd_list", "bd_ready"],
 }
 
-CONFIG_PATH = get_config_path()
+# CONFIG_PATH was a module-level constant. REMOVED: it cached the
+# repo-root config.toml at import time, so any test calling
+# save_config() or load_config() after import wrote/read the
+# user's actual config — corrupting the user's settings every test
+# run. The path is now re-resolved on every call, so the SLOP_CONFIG
+# env var (or a set_config_path() helper from test fixtures) can
+# redirect reads/writes to a temp_workspace without reimporting.
+# See tests/conftest.py:reset_paths for the test-side mechanism.
 
 #region: Config Utilities
 
@@ -160,7 +167,7 @@ def load_config() -> dict[str, Any]:
  """
   [C: src/multi_agent_conductor.py:ConductorEngine.__init__]
  """
- with open(CONFIG_PATH, "rb") as f:
+ with open(get_config_path(), "rb") as f:
   return tomllib.load(f)
 
 def save_config(config: dict[str, Any]) -> None:
@@ -172,11 +179,14 @@ def save_config(config: dict[str, Any]) -> None:
  config = _clean_nones(config)
  sys.stderr.write(f"[DEBUG] Saving config. Theme: {config.get('theme')}\n")
  sys.stderr.flush()
- with open(CONFIG_PATH, "wb") as f:
+ with open(get_config_path(), "wb") as f:
   tomli_w.dump(config, f)
 
 #region: History Utilities
 
+
+#region: History Utilities
+
 def parse_history_entries(history_strings: list[str], roles: list[str]) -> list[dict[str, Any]]:
  import re
  from src import thinking_parser