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/lib/types.ts

@@ -2256,6 +2256,13 @@ export interface LaneNode {
   label: string;
   icon: string;
   gate: boolean;
+  /** The one command that drives this node — a slash command
+   *  (`/superpowers:writing-plans`) or a shell one (`ccam lanes hook ci-gate`),
+   *  from the pipeline template. Empty string for a node with no single driver
+   *  (`done`, or a gate another agent declares). Display text only; the
+   *  dashboard never runs it. Optional in the type only because the archived
+   *  fixtures and older snapshots predate it; the server always sends the key. */
+  command?: string;
   state: "done" | "current" | "passed-no-evidence" | "failed" | "pending";
   /** Whether the server's stage-detection heuristic saw evidence of this stage
    *  from ingested tool events, independent of `state` (which is only set by an
@@ -2485,6 +2492,9 @@ export interface PipelineNodeStat {
   label: string;
   icon: string;
   gate: boolean;
+  /** Same per-node driver command as {@link LaneNode.command}; empty when the
+   *  template names none for this node. */
+  command?: string;
   entered: number;
   passed: number;
   withEvidence: number;