feat(v1.1.5): files SDK + files:* triggers

Filesystem-backed blob storage as the fifth concrete trigger kind.

- `files::collection(c).{create,head,get,update,delete,list}` Rhai SDK
  (blob in/out; metadata maps; missing-field throws naming the field).
- `FilesService` trait in picloud-shared; `FsFilesRepo` (atomic
  write: temp→fsync→rename→fsync-dir→DB; single-pass SHA-256;
  checksum-verified reads → Corrupted) + `FilesServiceImpl` in
  manager-core. Metadata in Postgres (0018), bytes on disk under
  PICLOUD_FILES_ROOT with 0o700 shard dirs.
- `files:*` trigger kind via the Layout-E pattern (0019: widen both
  CHECKs + files_trigger_details), TriggerEvent::Files (metadata only,
  no bytes), emit_files fan-out, dispatcher arm, admin endpoint
  POST /triggers/files (reuses validate_trigger_target).
- AppFilesRead/AppFilesWrite capabilities → script:read/script:write
  (seven-scope commitment held). AppPubsubPublish reserved for v1.1.6.
- Admin files API (list + delete) + dashboard Files view per app.

Cross-app isolation keyed on cx.app_id at every layer. ~45 new tests
(service in-memory, fs tempdir, bridge integration). No DB required
for the suite. publish_ephemeral and the orphan sweep stay deferred.

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

crates/executor-core/src/engine.rs

@@ -348,6 +348,7 @@ fn build_ctx_map(req: &ExecRequest) -> Map {
 /// `docs/v1.1.x-design-notes.md` §4 (the dead-letter sub-shape) and
 /// §2/blueprint §9 (KV). Each variant becomes a Rhai map with a
 /// `source` discriminant plus per-source fields.
+#[allow(clippy::too_many_lines)]
 fn trigger_event_to_dynamic(event: &TriggerEvent) -> Dynamic {
     let mut m = Map::new();
     m.insert("source".into(), event.source().into());
@@ -406,6 +407,33 @@ fn trigger_event_to_dynamic(event: &TriggerEvent) -> Dynamic {
             cron_map.insert("fired_at".into(), fired_at.to_rfc3339().into());
             m.insert("cron".into(), cron_map.into());
         }
+        TriggerEvent::Files {
+            op,
+            collection,
+            id,
+            name,
+            content_type,
+            size,
+            checksum,
+            prev,
+        } => {
+            m.insert("op".into(), op.as_str().into());
+            let mut files_map = Map::new();
+            files_map.insert("collection".into(), collection.clone().into());
+            files_map.insert("id".into(), id.clone().into());
+            files_map.insert("name".into(), name.clone().into());
+            files_map.insert("content_type".into(), content_type.clone().into());
+            files_map.insert(
+                "size".into(),
+                i64::try_from(*size).unwrap_or(i64::MAX).into(),
+            );
+            files_map.insert("checksum".into(), checksum.clone().into());
+            files_map.insert(
+                "prev".into(),
+                prev.clone().map_or(Dynamic::UNIT, json_to_dynamic),
+            );
+            m.insert("files".into(), files_map.into());
+        }
         TriggerEvent::DeadLetter {
             dead_letter_id,
             original,