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

AGENTS.md

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+<!-- TRELLIS:START -->
+# Trellis Instructions
+
+These instructions are for AI assistants working in this project.
+
+This project is managed by Trellis. The working knowledge you need lives under `.trellis/`:
+
+- `.trellis/workflow.md` — development phases, when to create tasks, skill routing
+- `.trellis/spec/` — package- and layer-scoped coding guidelines (read before writing code in a given layer)
+- `.trellis/workspace/` — per-developer journals and session traces
+- `.trellis/tasks/` — active and archived tasks (PRDs, research, jsonl context)
+
+If a Trellis command is available on your platform (e.g. `/trellis:finish-work`, `/trellis:continue`), prefer it over manual steps. Not every platform exposes every command.
+
+If you're using Codex or another agent-capable tool, additional project-scoped helpers may live in:
+- `.agents/skills/` — reusable Trellis skills
+- `.codex/agents/` — optional custom subagents
+
+Managed by Trellis. Edits outside this block are preserved; edits inside may be overwritten by a future `trellis update`.
+
+<!-- TRELLIS:END -->