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/workflows/LanePipelinePanel.tsx

@@ -139,9 +139,24 @@ export function LanePipelinePanel() {
               data-testid={`pipeline-stat-${n.id}`}
               className="flex items-center gap-2 text-xs"
             >
-              <span className="w-36 shrink-0 truncate text-fg-secondary" title={n.label}>
-                <span className="mr-1">{n.icon}</span>
-                {n.label}
+              {/* Label over the command that drives this node — the pass rate
+                  to the right answers "how often", this answers "by what". */}
+              <span className="w-44 shrink-0 overflow-hidden" title={n.label}>
+                <span className="block truncate text-fg-secondary">
+                  <span className="mr-1">{n.icon}</span>
+                  {n.label}
+                </span>
+                {n.command && (
+                  <button
+                    type="button"
+                    data-testid={`pipeline-stat-command-${n.id}`}
+                    title={t("lanes.copyCommand", { command: n.command })}
+                    onClick={() => void navigator.clipboard?.writeText(n.command || "")}
+                    className="block max-w-full truncate font-mono text-[10px] text-fg-muted hover:text-accent"
+                  >
+                    {n.command}
+                  </button>
+                )}
               </span>
 
               {/* Bars are scaled against the busiest node, not against each