Rewrite advanced benchmark framework guide

Lead with the supported typed Python workflows, document verified request and result contracts, and provide an executable lower-level extension example. Align API reference coverage and testing navigation with the three-part benchmark journey.

Author: AntoineRichard

docs/source/api/lab/isaaclab.benchmark.rst

@@ -34,7 +34,39 @@ isaaclab.benchmark
       MethodBenchmarkDefinition
       MethodBenchmarkRunner
       MethodBenchmarkRunnerConfig
+
+   .. rubric:: Measurements and metadata
+
+   .. autosummary::
+
+      BooleanMeasurement
+      DictMeasurement
+      DictMetadata
+      FloatMetadata
+      IntMetadata
+      ListMeasurement
+      Measurement
+      MetadataBase
+      SingleMeasurement
+      StatisticalMeasurement
+      StringMetadata
+      TestPhase
+
+   .. rubric:: Result schema
+
+   .. autosummary::
+
+      EnvironmentStepTiming
+      Learning
+      LearningCurve
+      MeanStd
       PlayBundle
+      Resources
+      RunConfig
+      RunIdentity
+      Runtime
       RuntimeBundle
       StartupBundle
+      StartupPhase
+      StartupTime
       TrainingBundle