refactor(lanes): drop the workflow skills and Superpowers link; pipelines go dormant

The plugin stops shipping its workflow layer:
- skills/ship-feature and skills/ship-feature-lane, the 18 stage/ship slash
  commands (plugin.json keeps agenthub-doctor/update/open), and all four
  agents/ (qc-local, senior-gate-reviewer, backend-reviewer, frontend-reviewer).
- CLI `agenthub skills install`, `agenthub lanes agents install`,
  `agenthub ship-full|ship-quick`; routes POST /api/skills/install and
  POST /api/lanes/:id/agents/install; the Settings button, the lane Tools
  menu item and the Add-lane setup step that called them.
- The Superpowers auto-install: server/lib/skill-plugins.js, the bootstrap's
  autoInstallSkillPlugins / skillPluginsSettled gate and the doctor row.

Pipelines are kept but dormant: server/data/pipelines/ is deleted, so no
template ships. `default` resolves to EMPTY_PIPELINE (no nodes, progress 0),
createLane still accepts it, POST /api/lanes/:id/stage answers 400
ENOPIPELINE, and the Workspace hides the stage timer, pickers, PipelineMap
and strip stage chip for a lane with no nodes. A template dropped into
DASHBOARD_PIPELINES_DIR turns it all back on. The server suite loads its
templates from server/__tests__/fixtures/pipelines/.

Docs: CLAUDE.md (marker, retired rules), README(.vi), INSTALL, ARCHITECTURE,
docs/LANES|PLUGINS|CLI|API, agenthub-introduction.html.

client/src/pages/Workspace.tsx

@@ -523,8 +523,10 @@ export function Workspace() {
   }, [refreshList]);
 
   const currentLane = selectedLaneId !== null ? lanes.find((l) => l.id === selectedLaneId) : null;
-  // Only claude lanes carry a pipeline (codex and antigravity emit no hooks).
-  const noPipeline = !!currentLane && currentLane.tool !== "claude";
+  // Only claude lanes carry a pipeline (codex and antigravity emit no hooks),
+  // and only while a template is installed — none ships, so it is dormant.
+  const noPipeline =
+    !!currentLane && (currentLane.tool !== "claude" || currentLane.pipeline_nodes.length === 0);
 
   // Feature list follows the selected lane, resets the viewer on lane switch.
   useEffect(() => {
@@ -817,8 +819,9 @@ export function Workspace() {
                     <Pencil className="h-3 w-3 shrink-0 text-fg-muted opacity-0 transition-opacity group-hover:opacity-100" />
                   </button>
                 )}
-                {/* Non-claude lanes carry no pipeline: no time-at-stage, no
-                    pipeline or feature picker, no map. */}
+                {/* A lane with no pipeline (non-claude, or no template
+                    installed): no time-at-stage, no pipeline or feature
+                    picker, no map. */}
                 {!noPipeline && (
                   <span className="shrink-0 tabular-nums text-xs text-fg-muted">
                     {since(currentLane.stage_seconds)}
@@ -882,7 +885,7 @@ export function Workspace() {
                   </>
                 )}
                 <div className="ml-auto flex items-center gap-2">
-                  {/* Per-lane actions (agents install, mcp sync, sync-base check)
+                  {/* Per-lane actions (mcp sync, sync-base check)
                     belong beside the lane they act on, not in a page header. */}
                   <LaneToolsMenu lane={currentLane} />
                   <button