feat(hw): add banked CAM pipeline with grouped read/write noise

- Add cam_core_banked.sv with 8-lane banked CAM core
- Add cam_write_noise.sv and cam_read_noise.sv for grouped noise injection
- Add noise_mask_grouped.sv generating grouped flip masks from 128-bit PRNG
- Add match_engine_pipeline.sv with multi-stage pipelined top-1 selection
- Add popcount_pipeline.sv for pipelined popcount operations
- Refactor test_cam_basic.py with parametrized DUT introspection helpers
- Add Python ref_model match_top1_with_read_noise() for read noise verification
- Update Makefile with separate WRITE_NOISE_* and READ_NOISE_* parameter groups
- Add new testbenches: test_cam_core_banked, test_cam_read_noise,
  test_cam_write_noise, test_match_engine_pipeline, test_ref_model_noise
  
breaking change hint: NUM_ROWS default changed from 512→4096, LANES from 16→8

hw/sim/tests/test_cam_read_noise.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+import cocotb
+from cocotb.clock import Clock
+from cocotb.triggers import RisingEdge
+
+
+async def reset_read_noise(dut):
+    dut.rst_n.value = 0
+    dut.valid_i.value = 0
+    dut.row_ids_i.value = 0
+    dut.hashes_i.value = 0
+    dut.lane_valid_i.value = 0
+    for _ in range(3):
+        await RisingEdge(dut.clk)
+    dut.rst_n.value = 1
+    for _ in range(2):
+        await RisingEdge(dut.clk)
+
+
+@cocotb.test()
+async def read_noise_disabled_forwards_hashes_after_one_stage(dut):
+    cocotb.start_soon(Clock(dut.clk, 10, unit="ns").start())
+    await reset_read_noise(dut)
+
+    LANES = 8
+    ROW_BITS = len(dut.row_ids_i) // LANES
+    HASH_BITS_PER_LANE = len(dut.hashes_i) // LANES
+
+    hashes = 0
+    rows = 0
+    for lane in range(LANES):
+        hashes |= (lane + 0x55) << (lane * HASH_BITS_PER_LANE)
+        rows |= lane << (lane * ROW_BITS)
+
+    dut.hashes_i.value = hashes
+    dut.row_ids_i.value = rows
+    dut.lane_valid_i.value = 0xFF
+    dut.valid_i.value = 1
+    await RisingEdge(dut.clk)
+    dut.valid_i.value = 0
+    await RisingEdge(dut.clk)
+    await RisingEdge(dut.clk)
+
+    assert int(dut.valid_o.value) == 1
+    assert int(dut.hashes_noisy_o.value) == hashes
+    assert int(dut.row_ids_o.value) == rows
+    assert int(dut.lane_valid_o.value) == 0xFF