refactor: 移除 Python 后端源码，全面迁移至 Rust gateway 架构

- 删除全部 Python 源码 (src/) 及 Alembic 迁移脚本，归档至 _deprecated_py_src/
- 重构 Rust gateway ai_pipeline: 拆分 planner/finalize 模块，新增 contracts/adaptation 层
- 重组 handlers 模块为 admin/public/proxy/internal/shared 子模块结构
- 新增 executor 模块，引入 Rust 原生数据库迁移 (aether-data/migrations)
- 简化 CI/Docker 构建流程，移除 base image 二级构建，统一为单一 app image
- 移除 Python 相关基础设施文件 (entrypoint.sh, gunicorn_conf.py, Dockerfile.base)

_deprecated_py_src/services/provider/adapters/kiro/constants.py

@@ -0,0 +1,95 @@
+"""Kiro adapter constants.
+
+Kiro upstream uses AWS Event Stream (binary frames) for streaming responses.
+"""
+
+from __future__ import annotations
+
+import platform
+
+AWS_EVENTSTREAM_CONTENT_TYPE = "application/vnd.amazon.eventstream"
+
+# Kiro API endpoints
+KIRO_GENERATE_ASSISTANT_PATH = "/generateAssistantResponse"
+KIRO_USAGE_LIMITS_PATH = "/getUsageLimits"
+
+# Default AWS region when not specified in credentials
+DEFAULT_REGION = "us-east-1"
+
+# Default client fingerprints used in headers (best-effort)
+DEFAULT_KIRO_VERSION = "0.8.0"
+DEFAULT_NODE_VERSION = "22.21.1"
+
+
+def _detect_system_version() -> str:
+    system = platform.system().lower() or "other"
+    release = platform.release() or "unknown"
+    # Match KiroIDE style: darwin#24.6.0, windows#10.0.22631, linux#6.8.0-...
+    return f"{system}#{release}"
+
+
+DEFAULT_SYSTEM_VERSION = _detect_system_version()
+
+# Header constants
+KIRO_AGENT_MODE = "vibe"
+CODEWHISPERER_OPTOUT = "true"
+
+# aws-sdk-js versions observed in kiro.rs
+AWS_SDK_JS_MAIN_VERSION = "1.0.27"
+AWS_SDK_JS_USAGE_VERSION = "1.0.0"
+
+# Claude model context window used by kiro.rs to convert contextUsage percentage -> tokens
+CONTEXT_WINDOW_TOKENS = 200_000
+
+# ---------------------------------------------------------------------------
+# Chunked-write policy injected into tool descriptions and system prompt
+# ---------------------------------------------------------------------------
+# Kiro upstream has lower per-message size limits than standard Claude.
+# We inject instructions for Write/Edit tools and a system-level policy
+# so the model splits large writes into smaller chunks automatically.
+
+WRITE_TOOL_DESCRIPTION_SUFFIX = (
+    "- IMPORTANT: If the content to write exceeds 150 lines, you MUST only write "
+    "the first 50 lines using this tool, then use `Edit` tool to append the "
+    "remaining content in chunks of no more than 50 lines each. If needed, leave "
+    "a unique placeholder to help append content. Do NOT attempt to write all "
+    "content at once."
+)
+
+EDIT_TOOL_DESCRIPTION_SUFFIX = (
+    "- IMPORTANT: If the `new_string` content exceeds 50 lines, you MUST split "
+    "it into multiple Edit calls, each replacing no more than 50 lines at a time. "
+    "If used to append content, leave a unique placeholder to help append content. "
+    "On the final chunk, do NOT include the placeholder."
+)
+
+TOOL_DESCRIPTION_SUFFIXES: dict[str, str] = {
+    "Write": WRITE_TOOL_DESCRIPTION_SUFFIX,
+    "Edit": EDIT_TOOL_DESCRIPTION_SUFFIX,
+}
+
+SYSTEM_CHUNKED_POLICY = (
+    "When the Write or Edit tool has content size limits, always comply silently. "
+    "Never suggest bypassing these limits via alternative tools. "
+    "Never ask the user whether to switch approaches. "
+    "Complete all chunked operations without commentary."
+)
+
+__all__ = [
+    "AWS_EVENTSTREAM_CONTENT_TYPE",
+    "AWS_SDK_JS_MAIN_VERSION",
+    "AWS_SDK_JS_USAGE_VERSION",
+    "CODEWHISPERER_OPTOUT",
+    "CONTEXT_WINDOW_TOKENS",
+    "DEFAULT_KIRO_VERSION",
+    "DEFAULT_NODE_VERSION",
+    "DEFAULT_REGION",
+    "DEFAULT_SYSTEM_VERSION",
+    "EDIT_TOOL_DESCRIPTION_SUFFIX",
+    "KIRO_AGENT_MODE",
+    "KIRO_GENERATE_ASSISTANT_PATH",
+    "KIRO_USAGE_LIMITS_PATH",
+    "SYSTEM_CHUNKED_POLICY",
+    "TOOL_DESCRIPTION_SUFFIXES",
+    "WRITE_TOOL_DESCRIPTION_SUFFIX",
+]