Refactor cpuif classes to use Interface abstraction (#14)

* Initial plan

* Refactor cpuif classes to use Interface abstraction

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* Fix type annotation consistency in Interface.signal()

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* Add runtime validation and documentation for indexer types

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* Remove unused variable in SVInterface.signal()

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* Fix master port directions in APB3 and APB4 flat interfaces

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* Fix AXI4LiteCpuifFlat and apply code formatting

Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

* PSELx -> PSEL

* cleanup marker warnings

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: arnavsacheti <36746504+arnavsacheti@users.noreply.github.com>

pyproject.toml

@@ -67,7 +67,7 @@ tools = ["pyrefly>=0.37.0", "ruff>=0.14.0"]
 [project.entry-points."peakrdl.exporters"]
 busdecoder = "peakrdl_busdecoder.__peakrdl__:Exporter"
 
-
+# ---------------------- RUFF ----------------------
 [tool.ruff]
 line-length = 110
 target-version = "py310"
@@ -106,3 +106,11 @@ untyped-def-behavior = "check-and-infer-return-type"
 
 project-includes = ["src/**/*"]
 project-excludes = ["**/__pycache__", "**/*venv/**/*"]
+
+# ---------------------- PYTEST ----------------------
+[tool.pytest.ini_options]
+python_files = ["test_*.py", "*_test.py"]
+markers = [
+    "simulation: marks tests as requiring cocotb simulation (deselect with '-m \"not simulation\"')",
+    "verilator: marks tests as requiring verilator simulator (deselect with '-m \"not verilator\"')",
+]