P1: host-agnostic quercus-core with agent loop, providers, and tool schemas

- Core types: Rational time, EntityId, ActionBatch, PngBytes (no Pillow dep)
- Config: ~/.quercus/config.toml with 0600 perms, env var override for CI
- LLMProvider: Claude (anthropic SDK) and OpenAI-compatible endpoint
  (covers custom gateways and llama.cpp server mode); graceful degradation
  without API keys
- Tool schemas: 26 curated tools with JSON Schema and read_only flags
- AgentLoop: sync dialogue loop with confirmation gate (read-only batches
  bypass, rejected mutations are reported back to the LLM), PNG frame
  feedback for multimodal providers
- Session log: JSONL recording with frame sha256 hashes, replayable
- HostAdapter ABC (signatures only, aligned with OPP/1 method families)
- Mock LLM provider (scripted/replay/record) for network-free CI

Tests: 69 passed via uv run pytest (no network access)

.gitignore

@@ -0,0 +1,18 @@
+# 虚拟环境与构建产物
+.venv/
+__pycache__/
+*.py[cod]
+*.egg-info/
+build/
+dist/
+
+# 测试缓存
+.pytest_cache/
+.coverage
+
+# 本地密钥/会话数据（config.toml 权限 0600，不入库）
+.quercus/
+
+# 系统与编辑器
+.DS_Store
+.idea/