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/manager-core/src/outbox_repo.rs

@@ -27,6 +27,8 @@ pub enum OutboxSourceKind {
     DeadLetter,
     /// v1.1.4.
     Cron,
+    /// v1.1.5.
+    Files,
 }
 
 impl OutboxSourceKind {
@@ -38,6 +40,7 @@ impl OutboxSourceKind {
             Self::Docs => "docs",
             Self::DeadLetter => "dead_letter",
             Self::Cron => "cron",
+            Self::Files => "files",
         }
     }
 
@@ -49,6 +52,7 @@ impl OutboxSourceKind {
             "docs" => Some(Self::Docs),
             "dead_letter" => Some(Self::DeadLetter),
             "cron" => Some(Self::Cron),
+            "files" => Some(Self::Files),
             _ => None,
         }
     }