feat(workflows): show lane pipelines, drop the deep analytics charts

The Workflows page rendered eleven charts of Claude Code harness internals
(collaboration network, subagent effectiveness, patterns, model delegation,
error propagation, concurrency, complexity, compaction). Too specialized to
read and nothing to act on, so they are gone along with their i18n keys.

What is left is what a reader can act on: headline stats, Workflow-tool runs,
the spawning DAG, the tool flow and the per-session drill-in — plus a new
first section for this dashboard's OWN pipelines. LanePipelinePanel renders a
horizontally scrolling lane strip and the selected lane's PipelineMap,
reusing the Workspace components so a stage looks identical on both pages.

The panel is read-only: the console-never-writes-a-stage boundary applies
here too, so every lane action stays on the Workspace page. The workflows API
response shape is untouched.

Closes #6

client/README.md

@@ -178,7 +178,7 @@ client/
 │   │   ├── Sidebar.tsx
 │   │   ├── Layout.tsx
 │   │   ├── RemoteSources.tsx  # Remote Data Sources settings panel (SSH multi-machine collection)
-│   │   └── workflows/      # D3.js workflow visualization components (12 files)
+│   │   └── workflows/      # Workflows page panels: lane pipelines + D3 analytics (6 files)
 │   │
 │   ├── pages/              # Route pages
 │   │   ├── Dashboard.tsx      # Monitor / Analytics / Health tabs
@@ -230,7 +230,7 @@ graph TB
     Sessions[Sessions<br/>filterable table]
     Detail[SessionDetail<br/>agent hierarchy + timeline]
     Feed[ActivityFeed<br/>streaming event log]
-    Workflows[Workflows<br/>D3.js visualizations]
+    Workflows[Workflows<br/>Lane pipelines + D3 analytics]
     Settings[Settings<br/>pricing + notifications + hooks]
 
     App --> Layout