Add tool registry for tool windows

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_tools.py

@@ -0,0 +1,24 @@
+from hqt.tools import TOOLS, Tool
+
+
+def test_registry_has_the_three_tools():
+    assert set(TOOLS) == {"nvim", "lazygit", "shell"}
+
+
+def test_each_entry_is_a_tool():
+    assert all(isinstance(t, Tool) for t in TOOLS.values())
+
+
+def test_nvim_and_lazygit_have_commands():
+    assert TOOLS["nvim"].command == ["nvim"]
+    assert TOOLS["lazygit"].command == ["lazygit"]
+
+
+def test_shell_has_empty_command_meaning_default_shell():
+    assert TOOLS["shell"].command == []
+
+
+def test_labels_are_the_bare_tool_names():
+    assert TOOLS["nvim"].label == "nvim"
+    assert TOOLS["lazygit"].label == "lazygit"
+    assert TOOLS["shell"].label == "shell"