chore(backend): mypy strict clean + ruff format pass

Pre-merge sanity per devops checklist (ruff format --check, mypy --strict).

Type fixes:
- ORM models: `Mapped[dict]` → `Mapped[dict[str, Any]]` (audit, scenario, run,
  report, ttp, detection.artifact_files_json). Equivalent on Pydantic DTOs
  (TtpBase.params_schema_json, ScenarioStepBase.params_override_json).
- Rename `TtpRead.current_version` → `TtpRead.version` to mirror the ORM
  column (which itself was renamed in D-009 cleanup).
- Flask blueprints: add `-> ResponseReturnValue` to every view, plus typed
  UUID params on `_validate_step_consistency`.
- `templating/filters.py`: rewrite the conditional re2 import so mypy can
  narrow the union (`ModuleType | None`); the runtime branch on `_re2 is not
  None` removes the unused-ignore that was triggered by warn_unused_ignores.
- `pyproject.toml`: add `flask_login.*` and `pythonjsonlogger.*` to the
  `[[tool.mypy.overrides]]` `ignore_missing_imports` list (both ship without
  typed marker).
- Misc: drop stale `# type: ignore` comments (`app.py:36`,
  `rbac/decorators.py:35`) flagged by `warn_unused_ignores`. Keep
  `logging.JsonFormatter` ignore because the symbol exists at runtime but is
  not re-exported through the typed surface.

Formatting:
- `ruff format` applied (15 files normalized; line-length unchanged at 100).

Verification on this commit:
- `ruff check`  → All checks passed.
- `ruff format --check` → 68 files already formatted.
- `mypy --strict src` → Success: no issues found in 54 source files.
- `pytest tests/unit` → 49 passed.

backend/src/mimic/db/models/scenario.py

@@ -6,7 +6,7 @@ run start that every referenced host matches.
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 from uuid import UUID
 
 from sqlalchemy import (
@@ -45,9 +45,7 @@ class Scenario(UuidPkMixin, TimestampsMixin, Base):
         Enum(C2Type, name="c2_type", create_type=False),
         nullable=False,
     )
-    created_by_id: Mapped[UUID | None] = mapped_column(
-        ForeignKey("user.id", ondelete="SET NULL")
-    )
+    created_by_id: Mapped[UUID | None] = mapped_column(ForeignKey("user.id", ondelete="SET NULL"))
 
     engagement: Mapped[Engagement] = relationship(back_populates="scenarios")
     steps: Mapped[list[ScenarioStep]] = relationship(
@@ -78,7 +76,7 @@ class ScenarioStep(UuidPkMixin, TimestampsMixin, Base):
         ForeignKey("host.id", ondelete="RESTRICT"),
         nullable=False,
     )
-    params_override_json: Mapped[dict] = mapped_column(JSON, default=dict, nullable=False)
+    params_override_json: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict, nullable=False)
     delay_after_ms: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
 
     scenario: Mapped[Scenario] = relationship(back_populates="steps")