feat(dashboard): add decision board for strategy selection

Why:
- Compare is the wrong surface for two-stage family selection over the 10-doc set.

Changes:
- Add the Decision Tab; raise GET /experiments default/max so the board can load the grid client-side.

Impact:
- Operators pick fixed_size ±N vs semantic@Boundary from existing Experiments.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/benchmarking/routes.py

@@ -8,7 +8,7 @@ Endpoints:
   GET    /experiments          List all experiments
 """
 
-from fastapi import APIRouter
+from fastapi import APIRouter, Query
 from fastapi.responses import HTMLResponse
 
 from src.core.exceptions import BenchmarkError, QueryError
@@ -185,9 +185,15 @@ async def get_benchmark(experiment_id: str):
 
 
 @router.get("/experiments")
-async def list_experiments(document_id: str | None = None):
+async def list_experiments(
+    document_id: str | None = None,
+    offset: int = Query(0, ge=0),
+    limit: int = Query(200, ge=1, le=500),
+):
     """List all experiments, optionally filtered by document."""
-    result = benchmark_service.list_experiments(document_id=document_id)
+    result = benchmark_service.list_experiments(
+        document_id=document_id, offset=offset, limit=limit
+    )
     # Enrich with document filenames and best_strategy
     from src.storage import sqlite as db
     for item in result.get("items", []):