core/config: add the [trash] section

`[trash]` owns the one policy `delete_path` needs from the human: whether a
delete is a move to the desktop's trash (`enabled = true`, the default) or a
removal that cannot be undone (`false`, which is what the tool did before).

Unknown keys degrade to the defaults, the way `[mcp]` does, so a typo cannot
silently switch a destructive policy on. `reload()` re-reads the section.

tests/test_config/test_trash_section.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from plyngent.config import load
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+
+def test_trash_section_defaults(tmp_path: Path) -> None:
+    """Deletes go to the system trash unless the section says otherwise."""
+    path = tmp_path / "c.toml"
+    _ = path.write_text("", encoding="utf-8")
+    assert load(path).trash_config.enabled is True
+
+
+def test_trash_section_parse(tmp_path: Path) -> None:
+    path = tmp_path / "c.toml"
+    _ = path.write_text("[trash]\nenabled = false\n", encoding="utf-8")
+    assert load(path).trash_config.enabled is False
+
+
+def test_trash_section_typo_falls_back(tmp_path: Path) -> None:
+    """An unknown key or a bad type degrades to the defaults, like ``[mcp]``."""
+    path = tmp_path / "c.toml"
+    _ = path.write_text("[trash]\nenable = false\n", encoding="utf-8")
+    assert load(path).trash_config.enabled is True
+
+    path2 = tmp_path / "d.toml"
+    _ = path2.write_text('[trash]\nenabled = "no"\n', encoding="utf-8")
+    assert load(path2).trash_config.enabled is True
+
+
+def test_trash_section_survives_reload(tmp_path: Path) -> None:
+    path = tmp_path / "c.toml"
+    _ = path.write_text("[trash]\nenabled = false\n", encoding="utf-8")
+    store = load(path)
+    assert store.trash_config.enabled is False
+    _ = path.write_text("[trash]\nenabled = true\n", encoding="utf-8")
+    store.reload()
+    assert store.trash_config.enabled is True