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.

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

tests/agents/test_factory.py

@@ -21,8 +21,8 @@ from unittest.mock import patch
 from agents import Agent
 from agents.tool import FunctionTool
 
-from strix.agents.sdk_factory import build_strix_agent, make_child_factory
-from strix.agents.sdk_prompt import _resolve_skills, render_system_prompt
+from strix.agents.factory import build_strix_agent, make_child_factory
+from strix.agents.prompt import _resolve_skills, render_system_prompt
 
 
 # --- prompt renderer ----------------------------------------------------
@@ -60,7 +60,7 @@ def test_render_system_prompt_swallows_template_errors() -> None:
     """If the template path can't be resolved, return an empty string
     (not raise) — agent construction must never blow up on prompt load."""
     with patch(
-        "strix.agents.sdk_prompt.get_strix_resource_path",
+        "strix.agents.prompt.get_strix_resource_path",
         side_effect=RuntimeError("missing"),
     ):
         out = render_system_prompt(skills=[])
@@ -191,7 +191,7 @@ def test_make_child_factory_passes_scan_level_config() -> None:
         interactive=True,
         system_prompt_context={"scope_source": "test"},
     )
-    with patch("strix.agents.sdk_factory.render_system_prompt", side_effect=fake_render):
+    with patch("strix.agents.factory.render_system_prompt", side_effect=fake_render):
         factory(name="child", skills=["xss"])
 
     assert captured["scan_mode"] == "fast"