refactor: rename platform/ → sdk/ to avoid stdlib conflict

platform/ shadowed Python's stdlib platform module, breaking
aiogram/aiohttp/multidict at import time. Renamed to sdk/ and
updated all imports across core/, tests/, and adapter/telegram/.

platform/interface.py

@@ -1,97 +0,0 @@
-# platform/interface.py
-from __future__ import annotations
-
-from datetime import datetime
-from typing import Any, AsyncIterator, Literal, Protocol
-
-from pydantic import BaseModel
-
-
-class User(BaseModel):
-    user_id: str
-    external_id: str
-    platform: str
-    display_name: str | None = None
-    created_at: datetime
-    is_new: bool = False
-
-
-class Attachment(BaseModel):
-    url: str
-    mime_type: str
-    size: int | None = None
-    filename: str | None = None
-
-
-class MessageResponse(BaseModel):
-    message_id: str
-    response: str
-    tokens_used: int
-    finished: bool
-
-
-class MessageChunk(BaseModel):
-    """Один кусок стримингового ответа. При sync-режиме — единственный чанк с finished=True."""
-    message_id: str
-    delta: str
-    finished: bool
-    tokens_used: int = 0
-
-
-class UserSettings(BaseModel):
-    skills: dict[str, bool] = {}
-    connectors: dict[str, dict] = {}
-    soul: dict[str, str] = {}  # свободные поля: name, instructions и т.п. — без пресетов стилей
-    safety: dict[str, bool] = {}
-    plan: dict[str, Any] = {}
-
-
-class AgentEvent(BaseModel):
-    """Webhook-уведомление от платформы — агент закончил долгую задачу."""
-    event_id: str
-    user_id: str
-    chat_id: str
-    event_type: Literal["task_done", "task_error", "task_progress"]
-    payload: dict[str, Any] = {}
-
-
-class PlatformError(Exception):
-    def __init__(self, message: str, code: str = "PLATFORM_ERROR"):
-        super().__init__(message)
-        self.code = code
-
-
-class PlatformClient(Protocol):
-    async def get_or_create_user(
-        self,
-        external_id: str,
-        platform: str,
-        display_name: str | None = None,
-    ) -> User: ...
-
-    # Sync — используем сейчас
-    async def send_message(
-        self,
-        user_id: str,
-        chat_id: str,
-        text: str,
-        attachments: list[Attachment] | None = None,
-    ) -> MessageResponse: ...
-
-    # Streaming — дверь открыта, мок отдаёт один чанк
-    async def stream_message(
-        self,
-        user_id: str,
-        chat_id: str,
-        text: str,
-        attachments: list[Attachment] | None = None,
-    ) -> AsyncIterator[MessageChunk]: ...
-
-    async def get_settings(self, user_id: str) -> UserSettings: ...
-
-    async def update_settings(self, user_id: str, action: Any) -> None: ...
-
-
-class WebhookReceiver(Protocol):
-    """Регистрируется в боте. Платформа зовёт нас когда агент закончил долгую задачу."""
-    async def on_agent_event(self, event: AgentEvent) -> None: ...