backend: ruff lint fixes

- main.py: AsyncIterator from collections.abc (typing.AsyncIterator deprecated, UP035)
- geometry.py: TEAP first in import (isort: ALL_CAPS before MixedCase, I001)
- pyproject.toml: ignore RUF001/002/003 — Russian-language project legitimately
  uses Cyrillic lookalikes in comments/docstrings (МСК-66 etc).

Verified: ruff check . — All checks passed!

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/main.py

@@ -1,5 +1,5 @@
+from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
-from typing import AsyncIterator
 
 import sentry_sdk
 from fastapi import FastAPI

backend/app/services/generative/geometry.py

@@ -5,7 +5,7 @@ Stage 1b: greedy filling of rectangular MKD with 3 strategies. STRtree for colli
 Performance target: <=10s per variant; fallback acceptance 15s.
 """
 
-from app.schemas.concept import ConceptInput, ConceptVariant, FinancialModel, TEAP
+from app.schemas.concept import TEAP, ConceptInput, ConceptVariant, FinancialModel
 
 
 def generate_stub(payload: ConceptInput) -> list[ConceptVariant]:

backend/pyproject.toml

@@ -45,6 +45,9 @@ line-length = 100
 
 [tool.ruff.lint]
 select = ["E", "F", "I", "B", "UP", "N", "RUF", "ASYNC"]
+# RUF001/002/003 — ambiguous Unicode (Cyrillic vs Latin lookalikes).
+# Off because the project is Russian-language; comments/docstrings legitimately use Cyrillic.
+ignore = ["RUF001", "RUF002", "RUF003"]
 
 [tool.mypy]
 python_version = "3.12"