feat: 推理引擎数据模型与异常层（types/exceptions）及 httpx/jinja2 依赖

src/genesis/inference/__init__.py

@@ -0,0 +1,23 @@
+"""Genesis 推理引擎（统一 LLM 调用入口）。"""
+
+from .types import ChatMessage, ChatResult, Prompt, StructuredResult, TokenUsage
+from .exceptions import (
+    LLMError,
+    LLMNetworkError,
+    LLMNotConfiguredError,
+    LLMResponseError,
+    LLMTimeoutError,
+)
+
+__all__ = [
+    "ChatMessage",
+    "ChatResult",
+    "Prompt",
+    "StructuredResult",
+    "TokenUsage",
+    "LLMError",
+    "LLMNetworkError",
+    "LLMNotConfiguredError",
+    "LLMResponseError",
+    "LLMTimeoutError",
+]

src/genesis/inference/exceptions.py

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+from __future__ import annotations
+
+
+class LLMError(Exception):
+    """LLM 调用相关的异常基类（api-design §7 映射基底）"""
+
+
+class LLMNetworkError(LLMError):
+    """网络失败 / 5xx 重试耗尽（可重试语义）"""
+
+
+class LLMTimeoutError(LLMError):
+    """LLM 调用超时（api-error: LLM_TIMEOUT 502）"""
+
+
+class LLMNotConfiguredError(LLMError):
+    """Key / 模型缺失（api-error: LLM_NOT_CONFIGURED 503）"""
+
+
+class LLMResponseError(LLMError):
+    """响应结构损坏（JSON 解析失败等）"""

src/genesis/inference/types.py

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+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any, Literal
+
+
+@dataclass
+class TokenUsage:
+    """一次 LLM 调用的 token 用量（可观测性事件/统计用）"""
+    input_tokens: int = 0
+    output_tokens: int = 0
+
+
+@dataclass
+class ChatMessage:
+    """Chat Completions 消息"""
+    role: Literal["system", "user", "assistant"]
+    content: str
+
+
+@dataclass
+class ChatResult:
+    """chat() 的返回值"""
+    text: str
+    model: str
+    prompt_version: str
+    usage: TokenUsage
+    duration_ms: int
+    status: Literal["ok", "fallback", "failed"]
+    error: str | None = None
+
+
+@dataclass
+class StructuredResult:
+    """chat_structured() 的返回值（补丁 1：含 status 字段）"""
+    data: dict
+    raw_text: str
+    parse_attempts: int
+    model: str
+    prompt_version: str
+    usage: TokenUsage
+    duration_ms: int
+    status: Literal["ok", "fallback", "parse_error", "failed"]
+    error: str | None = None
+
+
+@dataclass
+class Prompt:
+    """Prompt 模板条目（name+version 唯一）"""
+    name: str
+    version: str
+    template: str