lib: Change Iterable to Collection for truthy checks

Change parameter types from Iterable[str] to Collection[str] wherever
the parameter is tested for emptiness (if not names). This satisfies
the new truthy-iterable mypy rule, since bare Iterable values are
always truthy even when empty.

Affected files:
- Distro.py: install, delete, select, _select, _select_by_name
- rpm.py: query_packages
- suse/Distro.py: _select_by_name
- Cmd.py (secrets): _match_files, _list_template_files, etc.
- DistroContext.py: list_template_files, list_secret_paths, etc.

Assisted-by: unsloth/Qwen3.6-35B-A3B-GGUF:IQ4_NL and pi.dev 0.81.1
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/distros/suse/Distro.py

@@ -6,6 +6,7 @@ from ...Distro import Distro as Base
 from ...pm.rpm import list_files, query_packages, run_rpm
 
 if TYPE_CHECKING:
+    from collections.abc import Collection
     from typing import Iterable
 
     from ...base import Result
@@ -68,7 +69,7 @@ class Distro(Base):
         return False
 
     @override
-    async def _select_by_name(self, names: Iterable[str]) -> Iterable[Package]:
+    async def _select_by_name(self, names: Collection[str]) -> Iterable[Package]:
         return await query_packages(names, ec = self.ctx)
 
     @override