feat(evaluation): session catalog, user export import, and eval web UI

- Extend evaluation API: schemas, router, repo, admin and execution services
- Improve user export markdown importer; add fixtures and importer tests
- Session catalog repo/service updates; internal app wiring and docs
- Add internal-eval.sh helper; refresh app-eval-web (App, styles, Vite)

api/app/features/evaluation/admin_service.py

@@ -26,16 +26,25 @@ from app.features.evaluation.models import (
     EvalRunTurn,
     EvalVersion,
 )
+from app.features.evaluation.presenters import run_out
 from app.features.evaluation.schemas import (
     CaseCreate,
     ExperimentCreate,
     ImportJsonCaseBody,
     ImportMarkdownBody,
     RegressionSetCreate,
+    SessionEvalRunItem,
+    SessionEvalRunsOut,
     SnapshotFromConversationBody,
     VersionCreate,
 )
 from app.features.evaluation.session_catalog_service import SessionCatalogService
+from app.features.evaluation.user_export_fixtures import (
+    list_user_export_fixture_names as list_user_export_md_filenames,
+)
+from app.features.evaluation.user_export_fixtures import (
+    read_user_export_fixture,
+)
 from app.tasks.evaluation_tasks import run_eval_experiment_task
 
 
@@ -188,6 +197,23 @@ class EvaluationAdminService:
     async def list_experiments(self, *, limit: int) -> list[EvalExperiment]:
         return await eval_repo.list_experiments(self._db, limit=limit)
 
+    async def list_session_evaluation_runs(
+        self, conversation_id: str
+    ) -> SessionEvalRunsOut:
+        rows = await eval_repo.list_runs_for_source_conversation(
+            self._db, source_conversation_id=conversation_id
+        )
+        items: list[SessionEvalRunItem] = []
+        for run, _case, exp in rows:
+            turns = await eval_repo.list_turns(self._db, run.id)
+            items.append(
+                SessionEvalRunItem(
+                    experiment_name=exp.name,
+                    run=run_out(run, turns),
+                )
+            )
+        return SessionEvalRunsOut(conversation_id=conversation_id, items=items)
+
     async def create_experiment(self, body: ExperimentCreate) -> EvalExperiment:
         rs = await eval_repo.get_regression_set(self._db, body.regression_set_id)
         if not rs:
@@ -232,7 +258,6 @@ class EvaluationAdminService:
     async def experiment_stream_snapshot(
         self, experiment_id: str
     ) -> dict[str, Any] | None:
-        from app.features.evaluation.presenters import run_out
         from app.features.evaluation.schemas import GateVerdictOut
 
         exp = await eval_repo.get_experiment(self._db, experiment_id)
@@ -250,3 +275,10 @@ class EvaluationAdminService:
             "runs": run_payload,
             "gate": GateVerdictOut.model_validate(gv).model_dump() if gv else None,
         }
+
+    def list_user_export_fixture_names(self) -> list[str]:
+        return list_user_export_md_filenames()
+
+    def load_user_export_fixture_turns(self, filename: str) -> list[tuple[str, str]]:
+        turns, _ = read_user_export_fixture(filename)
+        return turns