feat(events): open the event contract to modules (Phase 7)

MODULE_API 1.10.0. Four names forwarded on the module-facing `api` --
registerEventActions, registerEventBudgets, registerEventLeases and
registerEventOptionSources -- one new route, and one rule made real: a
`cost()` naming a dimension no module declared is refused.

Only one of the four is new machinery. The action registry has staged
core's three actions on every boot since Phase 1; what it never had was a
way in, because loader.js builds its own `api` facade and had no method
that delegated to it. So the registry a module now reaches is one that has
been exercised on every boot for six phases.

Four decisions, settled 2026-09-03, all as recommended:

- Option sources are their own registration, modelled on registerAudiences,
  because a catalog has more than one consumer.
- An undeclared dimension is refused -- at save, at the dry run and at
  dispatch -- with its own code, because the fix is a module's declaration
  and not a deployment's cap.
- A lease is declared here and acquired by nothing; the ledger is Phase 8.
- Core registers core.options.legs, so an announce leg is a dropdown rather
  than the free-text box whose typo Phase 6's walk caught mid-run.

Proved with a throwaway module through the real loader, not with module-uo:
eventModuleContract.test.js writes a module to a real directory and lets the
loader scan it, covering all five envelope failure shapes, verify: true, the
four id spaces and dormancy on uninstall.

The live walk found the one defect nothing else could: the option-source
loader wrote its "already asked?" guard inside a setState updater and read
it on the next line, so the request was never made and the field sat on
"Reading the list..." for ever. It is a useRef now.

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T6t8mrAWhZU5vnyYgZTMtL

client/src/routes/admin/views/EventActions.jsx

@@ -99,7 +99,7 @@ export default function EventActions() {
       await load()
       setDrafts((d) => {
         const next = { ...d }
-        for (const dimension of action.dimensions) delete next[`${action.id}:${dimension}`]
+        for (const d of action.dimensions) delete next[`${action.id}:${d.id}`]
         return next
       })
       setNotice(`Saved ${action.label}.`)
@@ -113,7 +113,7 @@ export default function EventActions() {
   /** The caps this row would save: the drafts on top of what is stored. */
   const capsOf = (action) => {
     const out = {}
-    for (const dimension of action.dimensions) {
+    for (const { id: dimension } of action.dimensions) {
       const draft = drafts[`${action.id}:${dimension}`]
       const value = draft !== undefined ? draft : action.caps[dimension]
       if (value === '' || value === undefined || value === null) continue
@@ -130,7 +130,7 @@ export default function EventActions() {
   }
 
   const dirty = (action) =>
-    action.dimensions.some((d) => drafts[`${action.id}:${d}`] !== undefined)
+    action.dimensions.some((d) => drafts[`${action.id}:${d.id}`] !== undefined)
 
   if (loading) return <Loading />
   if (error) return <ErrorState message={error} />
@@ -218,20 +218,48 @@ export default function EventActions() {
                 run gets.
               </p>
               <div style={{ display: 'flex', gap: 10, flexWrap: 'wrap', alignItems: 'flex-end' }}>
-                {action.dimensions.map((dimension) => (
-                  <label key={dimension} className="sans" style={{ fontSize: '0.8rem' }}>
-                    <span className="dim" style={{ display: 'block', marginBottom: 2 }}>{dimension}</span>
-                    <input
-                      type="number"
-                      min="0"
-                      step="1"
-                      style={{ width: 110 }}
-                      value={capValue(action, dimension)}
-                      disabled={busy === action.id}
-                      onChange={(e) =>
-                        setDrafts((d) => ({ ...d, [`${action.id}:${dimension}`]: e.target.value }))
-                      }
-                    />
+                {action.dimensions.map((d) => (
+                  <label key={d.id} className="sans" style={{ fontSize: '0.8rem' }}>
+                    {/*
+                      The LABEL, with the unit beside the box — both from the module's
+                      `registerEventBudgets` declaration (Phase 7). Before it, this said
+                      `uo.creatures` over an unlabelled number, which is ambiguous in exactly
+                      the case that matters: 30 of what?
+                     */}
+                    <span className="dim" style={{ display: 'block', marginBottom: 2 }}>
+                      {d.registered ? d.label : d.id}
+                    </span>
+                    <span style={{ display: 'flex', alignItems: 'baseline', gap: 6 }}>
+                      <input
+                        type="number"
+                        min="0"
+                        step="1"
+                        style={{ width: 110 }}
+                        value={capValue(action, d.id)}
+                        disabled={busy === action.id || !d.registered}
+                        onChange={(e) =>
+                          setDrafts((s) => ({ ...s, [`${action.id}:${d.id}`]: e.target.value }))
+                        }
+                      />
+                      {d.registered && d.unit && (
+                        <span className="dim" style={{ fontSize: '0.75rem' }}>{d.unit}</span>
+                      )}
+                    </span>
+                    {/*
+                      A dimension nobody declares is SHOWN rather than hidden. The action is
+                      refused when it is saved into a step and again if it is ever dispatched,
+                      so the operator needs to be told which module is incomplete — hiding the
+                      row would make a broken module look like a cheap one.
+                     */}
+                    {!d.registered && (
+                      <span
+                        className="sans"
+                        style={{ display: 'block', marginTop: 2, fontSize: '0.72rem', color: '#d98b84' }}
+                      >
+                        No module declares this as a budget, so a step using this action is
+                        refused. It cannot be capped until one does.
+                      </span>
+                    )}
                   </label>
                 ))}
                 <button