refactor: nuke legacy harness, drop sdk_ prefixes

The SDK harness is the only path now; legacy host-side code is gone.
File names no longer carry the ``sdk_`` distinction.

Deleted legacy host-side modules:
- strix/agents/StrixAgent/ (template moved to strix/agents/prompts/)
- strix/agents/base_agent.py, state.py
- strix/llm/llm.py, config.py
- strix/runtime/docker_runtime.py, runtime.py
- strix/tools/executor.py, agents_graph/agents_graph_actions.py
- strix/interface/sdk_dispatch.py + the env-flag dispatch in cli.py

Renamed (drop ``sdk_`` prefix):
- strix/sdk_entry.py → strix/entry.py
- strix/agents/sdk_factory.py → strix/agents/factory.py
- strix/agents/sdk_prompt.py → strix/agents/prompt.py
- strix/tools/<x>/<x>_sdk_tool[s].py → strix/tools/<x>/tool[s].py
- strix/tools/_legacy_adapter.py → strix/tools/_state_adapter.py
- ``_legacy`` aliases inside the wrappers → ``_impl``

CLI + TUI now call ``run_strix_scan`` directly — they build the
sandbox image / sources_path locally and rely on
``session_manager.cleanup`` (called inside ``run_strix_scan``'s finally)
for teardown. Three TUI handlers that reached into legacy multi-agent
globals (``_agent_instances``, ``send_user_message_to_agent``,
``stop_agent``) are now no-ops with a TODO; reconnecting them to the
``AgentMessageBus`` is a follow-up.

Tracer.get_total_llm_stats no longer reaches into the deleted
``agents_graph_actions`` globals — the orchestration hooks now feed the
tracer via ``Tracer.record_llm_usage`` (live + completed buckets).
finish_scan's ``_check_active_agents`` and load_skill's runtime
``_agent_instances`` reach-in are no-op stubs; the
``AgentMessageBus`` is the source of truth post-migration.

llm/utils.py rewritten to keep only the streaming-parser helpers
(``normalize_tool_format``, ``parse_tool_invocations``,
``fix_incomplete_tool_call``, ``format_tool_call``, ``clean_content``).
``STRIX_MODEL_MAP`` moved to ``llm/multi_provider_setup.py`` (its only
remaining caller).

Per-file ruff ignores added for legacy interface modules (TUI / main /
CLI / utils / streaming_parser / tool_components) and tracer.py —
pre-existing PLC0415/BLE001/PLR0915 patterns are out of scope.

Tests: 287/287 passing. Renamed test files to drop ``sdk_`` prefix.
``test_tracer.py::test_get_total_llm_stats_aggregates_live_and_completed``
rewritten to feed ``Tracer.record_llm_usage`` instead of legacy globals.
Test file annotations added so pre-commit's strict mypy passes.

strix/interface/main.py

@@ -20,7 +20,7 @@ from rich.text import Text
 
 from strix.config import Config, apply_saved_config, save_current_config
 from strix.config.config import resolve_llm_config
-from strix.llm.utils import resolve_strix_model
+from strix.llm.multi_provider_setup import STRIX_MODEL_MAP
 
 
 apply_saved_config()
@@ -42,7 +42,9 @@ from strix.interface.utils import (  # noqa: E402
     validate_config_file,
     validate_llm_response,
 )
-from strix.runtime.docker_runtime import HOST_GATEWAY_HOSTNAME  # noqa: E402
+
+
+HOST_GATEWAY_HOSTNAME = "host.docker.internal"
 from strix.telemetry import posthog  # noqa: E402
 from strix.telemetry.tracer import get_global_tracer  # noqa: E402
 
@@ -50,7 +52,7 @@ from strix.telemetry.tracer import get_global_tracer  # noqa: E402
 logging.getLogger().setLevel(logging.ERROR)
 
 
-def validate_environment() -> None:  # noqa: PLR0912, PLR0915
+def validate_environment() -> None:
     console = Console()
     missing_required_vars = []
     missing_optional_vars = []
@@ -209,8 +211,13 @@ async def warm_up_llm() -> None:
 
     try:
         model_name, api_key, api_base = resolve_llm_config()
-        litellm_model, _ = resolve_strix_model(model_name)
-        litellm_model = litellm_model or model_name
+        # ``strix/<alias>`` is routed through the Strix proxy (OpenAI-compatible);
+        # everything else is sent as-is.
+        litellm_model: str | None = model_name
+        if model_name and model_name.startswith("strix/"):
+            base = model_name[len("strix/") :]
+            if base in STRIX_MODEL_MAP:
+                litellm_model = f"openai/{base}"
 
         test_messages = [
             {"role": "system", "content": "You are a helpful assistant."},
@@ -233,7 +240,7 @@ async def warm_up_llm() -> None:
 
         validate_llm_response(response)
 
-    except Exception as e:  # noqa: BLE001
+    except Exception as e:
         error_text = Text()
         error_text.append("LLM CONNECTION FAILED", style="bold red")
         error_text.append("\n\n", style="white")
@@ -260,7 +267,7 @@ def get_version() -> str:
         from importlib.metadata import version
 
         return version("strix-agent")
-    except Exception:  # noqa: BLE001
+    except Exception:
         return "unknown"
 
 
@@ -401,7 +408,7 @@ Examples:
                 args.instruction = f.read().strip()
                 if not args.instruction:
                     parser.error(f"Instruction file '{instruction_path}' is empty")
-        except Exception as e:  # noqa: BLE001
+        except Exception as e:
             parser.error(f"Failed to read instruction file '{instruction_path}': {e}")
 
     args.targets_info = []
@@ -544,7 +551,7 @@ def persist_config() -> None:
         save_current_config()
 
 
-def main() -> None:  # noqa: PLR0912, PLR0915
+def main() -> None:
     if sys.platform == "win32":
         asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())