feat: init mlkem project with Verilator test framework

- sync_rtl/common/: skid_buffer, pipeline_reg, defines (valid/ready)
- sync_rtl/mod_add/: modular adder example with Verilator C++ TB
- test_framework/: Python-driven Verilator compile/sim/compare pipeline
- test_framework/modules/mod_add/: 50-vector test plan, full鏈路 PASS
- .trellis/spec/: RTL and test_framework conventions documented

.trellis/.gitignore

@@ -0,0 +1,32 @@
+# Developer identity (local only)
+.developer
+
+# Current task pointer (each dev works on different task)
+.current-task
+
+# Session/window scoped runtime state
+.runtime/
+
+# Ralph Loop state file
+.ralph-state.json
+
+# Agent runtime files
+.agents/
+.agent-log
+.session-id
+
+# Task directory runtime files
+.plan-log
+
+# Atomic update temp files
+*.tmp
+
+# Update backup directories
+.backup-*
+
+# Conflict resolution temp files
+*.new
+
+# Python cache
+**/__pycache__/
+**/*.pyc