feat(v1.1.5): pubsub::publish_durable SDK + pubsub:* triggers

Durable pub/sub through the universal outbox — the sixth trigger kind.

- `pubsub::publish_durable(topic, message)` Rhai SDK (no handle; topics
  ARE the grouping unit). Message JSON-encoded; Blobs base64 at any
  depth.
- `PubsubService` trait in picloud-shared with the topic matcher +
  validator (exact / `<prefix>.*` / `*`; mid-pattern wildcards
  rejected). `PostgresPubsubRepo` + `PubsubServiceImpl` in manager-core.
- Publish-time fan-out: one outbox row per matching enabled pubsub
  trigger, all in ONE transaction (no half-fan-out on crash). No
  matching trigger → publish succeeds silently, zero rows.
- `pubsub:*` trigger kind via Layout-E (0020: widen both CHECKs +
  pubsub_trigger_details + partial index), TriggerEvent::Pubsub +
  ctx.event.pubsub, dispatcher arm, admin endpoint POST /triggers/pubsub
  (validates topic pattern + reuses validate_trigger_target).
- AppPubsubPublish capability → script:write (seven-scope held).
- Dashboard Pub/Sub trigger form on the Triggers tab + list rendering.

publish_ephemeral stays deferred to v1.2. ~18 new tests (service
in-memory incl. transactional-rollback, shared matcher, bridge
encoding). No DB required for the suite.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/executor-core/src/engine.rs

@@ -434,6 +434,20 @@ fn trigger_event_to_dynamic(event: &TriggerEvent) -> Dynamic {
             );
             m.insert("files".into(), files_map.into());
         }
+        TriggerEvent::Pubsub {
+            topic,
+            message,
+            published_at,
+        } => {
+            // `ctx.event.op` is always "publish" for pub/sub (the only
+            // op a publish produces).
+            m.insert("op".into(), "publish".into());
+            let mut ps = Map::new();
+            ps.insert("topic".into(), topic.clone().into());
+            ps.insert("message".into(), json_to_dynamic(message.clone()));
+            ps.insert("published_at".into(), published_at.to_rfc3339().into());
+            m.insert("pubsub".into(), ps.into());
+        }
         TriggerEvent::DeadLetter {
             dead_letter_id,
             original,