chore(lint): auto-fix 253 of 283 ruff issues (F401, I001, E402, RUF100, UP037, SIM105)

Mass ruff auto-fix:
  - ruff check --fix: 109 issues fixed (F401 unused imports,
    I001 unsorted imports, UP037 quoted annotations, SIM105
    suppressible exception, RUF100 unused-noqa)
  - ruff check --fix --unsafe-fixes: 22 additional issues
  - ruff format: 70 files reformatted
  - Manual pass: fix 16 misplaced import httpx lines
  - Manual pass: fix remaining E402 (import-after-docstring)

Result: 283 errors -> 30 errors.

The remaining 30 are real issues that need manual review:
  5 F401 unused-import (likely auto-generated stubs)
  5 F821 undefined-name (real bugs in code that references
    redis/pydantic/LLMRegistry without imports)
  3 BLE001 (the compliance LLM fallback is intentional; the
    other two are real)
  3 RUF012 mutable-class-default
  3 SIM105, 3 SIM117, 2 E722, 2 E741
  1 B007, 1 B025, 1 E402, 1 RUF200 (pyproject.toml issue)

Tests: 436/437 pass (1 pre-existing SSE sandbox failure).
format check + import sort: now clean.
make ci: still gated on the 30 remaining real issues.
Follow-up: triage the 30 issues file-by-file.

tests/test_llm_providers.py

@@ -30,15 +30,21 @@ def test_llm_registry_register() -> None:
 
     class FakeProvider(LLMProvider):
         name = "fake"
-        async def complete(self, *args, **kwargs): return LLMResponse(text="ok", model="fake", provider="fake")
-        async def embed(self, *args, **kwargs): return [0.1, 0.2]
+
+        async def complete(self, *args, **kwargs):
+            return LLMResponse(text="ok", model="fake", provider="fake")
+
+        async def embed(self, *args, **kwargs):
+            return [0.1, 0.2]
 
     r.register(FakeProvider())
     assert "fake" in r.providers
 
 
 def test_llm_response_dataclass() -> None:
-    r = LLMResponse(text="hello", model="m", provider="p", input_tokens=10, output_tokens=5, cost_usd=0.001)
+    r = LLMResponse(
+        text="hello", model="m", provider="p", input_tokens=10, output_tokens=5, cost_usd=0.001
+    )
     assert r.text == "hello"
     assert r.cost_usd == 0.001
 
@@ -47,8 +53,13 @@ def test_provider_cost_estimation() -> None:
     class TestProvider(LLMProvider):
         cost_per_1k_input = 0.001
         cost_per_1k_output = 0.002
-        async def complete(self, *args, **kwargs): return LLMResponse(text="", model="t", provider="t")
-        async def embed(self, *args, **kwargs): return []
+
+        async def complete(self, *args, **kwargs):
+            return LLMResponse(text="", model="t", provider="t")
+
+        async def embed(self, *args, **kwargs):
+            return []
+
     p = TestProvider()
     cost = p.estimate_cost(1000, 500)
     assert abs(cost - 0.002) < 0.0001  # 0.001 + 0.001
@@ -58,5 +69,6 @@ def test_referral_link_format() -> None:
     rc = ReferralConfig()
     for provider, link in rc.referral_links.items():
         # FlareSolverr is open-source, no affiliate
-        if provider == "flaresolverr": continue
+        if provider == "flaresolverr":
+            continue
         assert "pry" in link, f"Link for {provider} missing referral: {link}"