feat: enhance PDK support and add test coverage

- Updated gen_iverilog_filelist.py to exclude sequential models from the file list for GF180 PDK.
- Introduced black box definitions for GF180 and SKY130 IO cells in their respective .sv files.
- Added simulation models for GF180 IO cells and sequential cells in gf180_seq_sim_cells.v.
- Modified tc_clk.sv to utilize specific clock cells for GF180 and SKY130 PDKs.
- Implemented bi-directional and tri-state pad modules for GF180 and SKY130 PDKs in tc_io.sv.
- Enhanced dependency lock validation to include submodule checks in dependency_lock.py.
- Updated setup_helpers.py to support selective submodule initialization.
- Created a comprehensive testbench for PDK cells in tc_pdk_cells_tb.sv.
- Added tests for dependency helper functions and tech cell configurations to ensure proper error handling.

tests/test_tech_cell_config.py

@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+@pytest.mark.parametrize(
+    ("profile", "pdk"),
+    (
+        ("configs/ci/hazard3-rv32im-gf180.mk", "GF180"),
+        ("configs/ci/hazard3-rv32im-sky130.mk", "SKY130"),
+    ),
+)
+def test_unqualified_pll_profiles_are_rejected(profile: str, pdk: str) -> None:
+    result = subprocess.run(
+        ("make", f"CONFIG={profile}", "HAVE_PLL=YES", "config"),
+        cwd=ROOT,
+        check=False,
+        capture_output=True,
+        text=True,
+    )
+
+    assert result.returncode != 0
+    assert f"HAVE_PLL=YES requires a qualified crystal pad and is unsupported for PDK={pdk}" in (
+        result.stdout + result.stderr
+    )