Add MkDocs Material documentation site with 40 pages and auto-generated API reference

Sets up a complete documentation website with 7 navigable sections (Home, Getting
Started, User Guide, Architecture, API Reference, Deployment, Development), light/dark
mode, search, code copy, and Mermaid diagram support. API reference pages use
mkdocstrings to auto-generate docs from source docstrings. GitHub Actions workflow
deploys to GitHub Pages on push to main.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/api/bench.md

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+# Benchmarks Module
+
+The benchmarks module provides a framework for measuring inference engine
+performance. All benchmarks implement the `BaseBenchmark` ABC and are
+registered via `BenchmarkRegistry`. The `BenchmarkSuite` runner executes
+a collection of benchmarks and aggregates results into JSONL or summary
+format.
+
+## Abstract Base Class and Runner
+
+### BaseBenchmark
+
+::: openjarvis.bench._stubs.BaseBenchmark
+    options:
+      show_source: true
+      members_order: source
+
+### BenchmarkResult
+
+::: openjarvis.bench._stubs.BenchmarkResult
+    options:
+      show_source: true
+      members_order: source
+
+### BenchmarkSuite
+
+::: openjarvis.bench._stubs.BenchmarkSuite
+    options:
+      show_source: true
+      members_order: source
+
+---
+
+## Benchmark Implementations
+
+### LatencyBenchmark
+
+::: openjarvis.bench.latency.LatencyBenchmark
+    options:
+      show_source: true
+      members_order: source
+
+### ThroughputBenchmark
+
+::: openjarvis.bench.throughput.ThroughputBenchmark
+    options:
+      show_source: true
+      members_order: source