chore: drop empty if TYPE_CHECKING: blocks and orphaned imports (ruff TC005)

[alexzhu0]

Summary

Ruff rule TC005 flags empty if TYPE_CHECKING: blocks — dead code left behind by previous refactors when every forward-reference import under the block was eventually removed. 28 occurrences outside generated code.

After deleting the empty block, the TYPE_CHECKING import becomes unused (F401) in the same file. This PR cleans both in one commit so each file is self-consistent; F401 is invoked only on files already touched by TC005, nothing else is rewritten.

-from typing import TYPE_CHECKING
-
 from sqlalchemy import Column, ForeignKey, String, UniqueConstraint
 from sqlalchemy.dialects.postgresql import UUID as PgUUID
 from sqlalchemy.orm import relationship

-if TYPE_CHECKING:
-    pass
-
-
 class Role(Principal):

Some files still have other unused imports the broader F401 sweep would clean up — those are deliberately out of scope here (I tried the global ruff --select F401 --fix and it cascaded into 90 files touching unrelated code). This PR is strictly the TC005 blast radius.

Scope

28 files, +19 / −84. Touched areas:

Layer	Files
Graph adapters	kuzu, remote_kuzu, neo4j_driver, neptune_driver
Vector adapters	ChromaDBAdapter
API / maintenance	episode_quality.py
Auth models	Role, Tenant
Core domain	Entity, Facet
Data models	Data, Dataset
LLM backends	baml acreate_structured_output, litellm_instructor openai adapter
Episodic memory	edge_text_generators, episode_builder/phase0c, episode_size_check, facet_entity_matcher, llm_tasks
Sync	SyncOperation
Tests	8 test files covering CLI, crawler e2e, descriptive metrics, permissions, s3, rate-limit retry, parallel DBs, neptune analytics

Verification

$ ruff check . --exclude 'm_flow/baml_client' --exclude 'm_flow-frontend' --select TC005
All checks passed!

$ for f in <every touched file>; do uv run python -c "import ast; ast.parse(open('$f').read())"; done
# clean across all 28 files

$ for mod in m_flow.auth.models.Role m_flow.core.domain.models.Entity \
             m_flow.data.models.Data m_flow.memory.episodic.episode_size_check; do
    uv run python -c "import $mod"
  done
# import ok: all sample modules

No behavior change. Generated code under m_flow/baml_client/ is untouched.

I affirm that all code in every commit of this pull request conforms to the terms of the M-flow Developer Certificate of Origin