feat: initialize cold display guard

docs/plans/2026-04-27-cold-display-guard.md

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+# Cold Display Guard Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Build a standalone Python project for refrigerated display food-batch timing and 3-hour disposal compliance alerts.
+
+**Architecture:** Keep camera and model logic outside the first business core. Implement a pure Python batch engine that consumes timestamped zone occupancy and trash-bin events, emits JSON-compatible compliance events, and can later be driven by a video adapter.
+
+**Tech Stack:** Python 3.11+ standard library, TOML config via `tomllib`, tests via `unittest`.
+
+---
+
+### Task 1: Project Skeleton
+
+**Files:**
+- Create: `pyproject.toml`
+- Create: `src/cold_display_guard/__init__.py`
+- Create: `README_zh.md`
+- Create: `config/example.toml`
+
+**Steps:**
+
+1. Create packaging metadata with a console script named `cold-display-guard`.
+2. Create a Chinese README documenting the confirmed business rules.
+3. Create default TOML config for camera id, thresholds, 4x2 zones, and trash ROI placeholder.
+4. Verify imports with `python3 -m unittest discover -s tests`.
+
+### Task 2: Batch Engine
+
+**Files:**
+- Create: `src/cold_display_guard/models.py`
+- Create: `src/cold_display_guard/engine.py`
+- Test: `tests/test_engine.py`
+
+**Steps:**
+
+1. Write tests for batch start, normal consumption, over-threshold pending disposal, trash confirmation, mixed-batch violation, overdue return violation, and missing disposal violation.
+2. Implement dataclasses for observations, batches, zones, and events.
+3. Implement `BatchEngine.process()`.
+4. Run `python3 -m unittest tests.test_engine -v`.
+
+### Task 3: Config and CLI
+
+**Files:**
+- Create: `src/cold_display_guard/config.py`
+- Create: `src/cold_display_guard/cli.py`
+- Test: `tests/test_config.py`
+
+**Steps:**
+
+1. Load TOML config into an engine settings dataclass.
+2. Add CLI support for processing a JSONL observation file.
+3. Write emitted events to stdout as JSONL.
+4. Run `python3 -m unittest discover -s tests -v`.
+
+### Task 4: Git
+
+**Steps:**
+
+1. Initialize git in `~/Code/cold_display_guard`.
+2. Review `git status --short`.
+3. Commit the initial project.