fix(events): carry a module's own account of a successful step

`EVENTS.md` §H told a module the revert contract accepts a `detail` on its
envelope. `classify()` reads `ok`, `retry`, `error`, `await`, `holdFor`,
`resources` and `participants` — and has never read a `detail`. So a module
that answered one was writing into nothing.

`module-uo` believed it, twice, since Phase 12b:

  * `uo.item.grant` answers `{ granted, missed, why }`
  * `uo.world.save` answers `{ started: true }`

The grant is the one that matters. A grant reaches the players a run's
participation ledger holds, and **which of them missed out is knowable only to
the module and reported nowhere else** — so an operator saw a step marked
`done` and never learned four of twelve got nothing.

Found writing the integration kit's chapter 5 (`Integration-kit#10`), whose
template made the same mistake on §H's authority.

## What this adds

`detail` becomes a real, optional member of the two SUCCESS envelopes, beside
`resources` and `participants` — on both, because `await: 'human'` is a success
and a cue's confirm finishes the step without a second dispatch, so that is the
only moment its module could ever have said anything.

**Core never interprets it.** `safeDetail()` bounds it and nothing else reads a
key out of it, here or in the runner or in the browser. That is the point: a
module knows things about its own verb core cannot compute, and it had no other
way to say them.

  * objects only — the column is JSON and the console renders keys, so a bare
    string has nothing to render under, and core inventing a key would be core
    interpreting it after all;
  * 4KB of serialised JSON, dropped rather than truncated, because half a JSON
    object is not a JSON object;
  * unserialisable (circular, a throwing `toJSON`) is dropped — reaching the
    runner would make the log INSERT throw, inside the one write documented
    never to;
  * re-parsed rather than passed through, so core holds no live reference into
    a module's object;
  * **anything wrong with it is dropped and logged, never a failure.** A step
    that did what it was asked must not be re-run because its module's
    commentary was malformed: that is a world write repeated for a log line.

The runner writes it as a `step.detail` run-log row, its own kind rather than a
field on `resource.recorded` — the grant that forced this ledgers nothing
(`reversible: 'none'`) and reports no participants, so it would have had
nowhere to ride.

## The renderer, which is half the fix

`describeLogLine`'s default returns a kind WORD, so a `step.detail` row falling
through would have rendered as the literal string "step.detail" — the channel
existing and showing nothing, exactly the failure being fixed. It gets a case
that renders whatever keys the module put there, generically: a switch on known
keys would be the browser learning one module's vocabulary.

    uo.item.grant — granted: 8, missed: 4, why: bank full, offline
    uo.world.save — started: true

**`module-uo` needs no change**: the code it already shipped starts working.

MODULE_API stays 1.10.0, amended in place — it is still on `edge`. Zero-line
route manifest diff; no route added. 2057 server tests, 400 client tests.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4

client/src/lib/eventAuthoring.js

@@ -692,9 +692,46 @@ const KIND_WORDS = {
   'step.refused': 'Refused',
   'run.budget': 'Caps',
   'version.verified': 'Dry run passed',
+  // Phase 15. "Reported" rather than "Detail": the line is the module talking
+  // about its own verb, and every other word here names something core did.
+  'step.detail': 'Step reported',
   note: 'Note',
 }
 
+// How deep and how long a module's own `detail` value is allowed to render.
+// The dispatcher already caps the whole object at 4KB, so this is about a line
+// staying a line — an operator scanning a run's log should not have one row
+// wrap eight times because a module answered with an array of forty names.
+const DETAIL_LIST_SHOWN = 5
+const DETAIL_TEXT_MAX = 80
+
+/**
+ * One value out of a module's `detail`, as text.
+ *
+ * **Core does not interpret these keys and neither does this.** A module wrote
+ * the object; the console shows it. That is the whole reason the renderer is
+ * generic rather than a switch — a switch would be core learning a module's
+ * vocabulary, which is the thing the module system exists to prevent.
+ */
+function detailValue(value) {
+  if (value === null || value === undefined) return '—'
+  if (Array.isArray(value)) {
+    const shown = value.slice(0, DETAIL_LIST_SHOWN).map(detailValue).join(', ')
+    return value.length > DETAIL_LIST_SHOWN
+      ? `${shown} and ${value.length - DETAIL_LIST_SHOWN} more`
+      : shown
+  }
+  if (typeof value === 'object') {
+    // A nested object is rendered by its keys rather than as JSON: an operator
+    // reading a log wants "granted: 8, missed: 4", not a brace.
+    return Object.entries(value)
+      .map(([k, v]) => `${k} ${detailValue(v)}`)
+      .join(', ')
+  }
+  const text = String(value)
+  return text.length > DETAIL_TEXT_MAX ? `${text.slice(0, DETAIL_TEXT_MAX - 1)}…` : text
+}
+
 export const logKindWord = (kind) => KIND_WORDS[kind] || kind
 
 /**
@@ -758,6 +795,22 @@ export function describeLogLine(line) {
         .join(', ') || 'no caps apply to this run'
     case 'version.verified':
       return `Version ${d.version} passed its dry run — scheduled occurrences may start`
+    // Phase 15. The one line whose body core did not compose: a module may answer
+    // a successful step with a `detail` object, and this renders whatever keys it
+    // put there. `action` is core's own and is pulled out to lead the sentence;
+    // everything after it is the module's.
+    //
+    // **Without this case the row would render as the literal string
+    // "step.detail"**, because the default below is a kind word and not a
+    // sentence — which would be the reporting channel existing and showing
+    // nothing, the exact failure it was built to fix.
+    case 'step.detail': {
+      const { action, ...rest } = d
+      const body = Object.entries(rest)
+        .map(([key, value]) => `${key}: ${detailValue(value)}`)
+        .join(', ')
+      return body ? `${action || 'A step'} — ${body}` : `${action || 'A step'} reported nothing`
+    }
     default:
       return logKindWord(line?.kind)
   }