Resolve adapters by what is mounted, and say why each kind is not loaded

runtime.py resolved adapters at 7 call sites and only ever looked in the
adapter library, so an adapter attached to a cartridge (cartridge.py:230
copies it into <cartridge>/adapters/{kind}/) was never loaded by anything.
Resolution now lives in adapters.py: it reads the mounted cartridge set,
prefers a mounted cartridge's copy over the library, and answers every one
of the six kinds with a state the facts support — loaded, available,
deferred (base_model mismatch or missing weights, both models named in the
reason), missing — plus a shadowed row for each adapter that lost the
choice. A mounted cartridge is the scenario selection; neither manifest
carries a scenario field, so none was invented.

Two bugs the new tests caught: the preference sort lost reverse=True, so a
library adapter beat a mounted cartridge's copy, and the load branch had
never been executed by a test. Stub weights now prove peft is asked to
attach, that the returned model is put in eval mode, and that the endpoint
reports loaded until unload clears it.

Faces: GET /api/runtime/adapters, `ely-eye adapters`, and a log line naming
the reason whenever a generation runs without an adapter.

Gates: 222 passed; ruff clean; mypy cold cache on the 7 touched files gives
the same 2 errors as HEAD's runtime.py, and pyright gives the same 2 as
HEAD — both are qwen_vl_utils typing artifacts (process_vision_info returns
2 or 3 values depending on return_video_kwargs; the product takes 2).

backend/src/ely_eye/api.py

@@ -10,6 +10,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel
 
 from . import __version__
+from .adapters import plan as adapter_plan
 from .api_cartridges import register as register_cartridge_routes
 from .api_holders import register as register_holder_routes
 from .benchmarks import (
@@ -41,6 +42,7 @@ from .proofs import HashHopEvaluator, PRDProofSuite
 from .research_modules import ResearchModuleService
 from .retrieval import RetrievalService
 from .runtime import QwenRuntime, RuntimeUnavailableError
+from .runtime_schemas import AdapterLoadReport
 from .schemas import (
     AdapterManifest,
     AdapterStatus,
@@ -277,6 +279,10 @@ def create_app() -> FastAPI:
     def runtime_profiles() -> RuntimeProfileReport:
         return runtime_profile_report()
 
+    @app.get("/api/runtime/adapters", response_model=AdapterLoadReport)
+    def runtime_adapters(settings: Annotated[Settings, Depends(settings_dep)]) -> AdapterLoadReport:
+        return adapter_plan(settings, Database(settings))
+
     @app.get("/api/research/modules")
     def research_modules(settings: Annotated[Settings, Depends(settings_dep)]):
         db = Database(settings)