feat(lanes): give every pipeline node its own driver command

A pipeline template named ONE command for the whole run (`skill`), so the
only way to know what actually moves a given node was to read that node's
`detect` regexes. Each node now carries its own `command`: a slash command
(`/superpowers:writing-plans`) or a shell one (`ccam lanes hook ci-gate`),
whichever its detect rules already watch for.

The values are derived from each node's own detect rules, not invented —
every `ccam …` string was checked against bin/ccam.js and every
`/superpowers:*` against the installed plugin. Nodes reaching which is a
declaration rather than an action (`done`, `merged`, `reported`,
`e2e-feature-passed`, `qc-plan`) are deliberately left empty.

`pipelines.js` normalizes a missing or non-string value to "", so a
custom template written before this field keeps loading rather than
rendering "undefined". `nodeStates()` and GET /api/lanes/pipeline-stats
pass it through. Never executed by the dashboard — display text, the same
contract `skill` already had.

Surfaced where each view has room for it: the Workflows pass-rate panel
shows it under the node label and copies it on click; PipelineMap folds
it into the node tooltip, because a 16-node pipeline has to fit across
one card and there is no width for a second line.

`command?: string` is optional in the client type only to spare four
unrelated test fixtures — the server always sends the key, and the UI has
to branch on the empty string regardless.

Verified: npm run test:server (1373, +3), npm run test:client (459, +2),
tsc --noEmit, prettier and check-headers clean. docs/LANES.md § Custom
template format documents the field. openapi.yaml needs no change: the
lane payload and pipeline-stats were never schematized there.

client/src/components/lanes/PipelineMap.tsx

@@ -49,11 +49,17 @@ export default function PipelineMap({
             data-testid={`pipeline-node-${n.id}`}
             data-state={n.state}
             data-detected={n.detected ? "true" : undefined}
-            title={
+            // The node's driver command rides along in the tooltip rather than
+            // on the pill: the map has to fit a 16-node pipeline across one
+            // card, so there is no width for a second line of text.
+            title={[
               n.detected && detectedSignal
                 ? `${n.label} ← ${detectedSignal}`
-                : `${n.label} — ${n.state}`
-            }
+                : `${n.label} — ${n.state}`,
+              n.command ? `→ ${n.command}` : null,
+            ]
+              .filter(Boolean)
+              .join("\n")}
             className={`flex min-w-0 flex-1 items-center justify-center gap-1.5 rounded-full border px-2 py-1.5 text-[11px] ${n.detected ? DETECTED_CLASS : STATE_CLASS[n.state]}`}
           >
             <span className="shrink-0 text-[13px] leading-none">{n.icon}</span>