feat(v1.1.3-modules): shared types, migrations, engine + resolver scaffold

Lays down the v1.1.3 plumbing:

- `ScriptKind` enum in `picloud-shared` ('endpoint' | 'module').
- `ModuleSource` trait + `ModuleScript` DTO + `NoopModuleSource` in
  `picloud-shared`. Resolver lives in `executor-core`; Postgres impl
  in `manager-core` (`PostgresModuleSource`).
- `Services::new` grows a fifth `modules: Arc<dyn ModuleSource>` arg.
- `ScriptValidator` returns `ValidatedScript { imports }` so the
  manager can populate the dep-graph table on save. New
  `validate_module` method on the trait gates module-shape rules.
- `Engine::execute_ast(&Arc<rhai::AST>, req)` lets the orchestrator's
  script cache reuse compiled ASTs. `Engine::execute(&str, req)` is
  preserved as a convenience that compiles inline. `Engine::compile`
  exposes the AST for callers that want to cache.
- `PicloudModuleResolver` replaces `DummyModuleResolver` per-call.
  Bridges Rhai's sync `ModuleResolver::resolve` to async
  `ModuleSource::lookup` via `Handle::block_on`. Enforces:
  - cross-app isolation (resolver captures `Arc<SdkCallCx>`),
  - circular import detection (in-progress stack on the resolver),
  - import depth limit (default 8 via
    `Limits::module_import_depth_max`).
- Module-shape validation walks `ast.statements()` via `rhai/internals`
  and accepts only `Var { CONSTANT }`, `Import`, and `Noop`. The
  manager admin endpoint runs `validate_module` at save (primary
  gate); resolver re-runs it at load (defense in depth).
- LRU cache `(AppId, name) -> (updated_at, Arc<Module>)` owned by
  `Engine`. Size from `PICLOUD_MODULE_CACHE_SIZE` (default 512).
- Migration `0015_scripts_kind.sql` adds `scripts.kind` + composite
  index + module-name shape CHECK.
- Migration `0016_script_imports.sql` adds the dep-graph table with
  FK CASCADE on both columns.
- Repo: `kind` threaded through SELECT/INSERT/UPDATE. New
  `count_routes_for_script` / `count_triggers_for_script` /
  `list_imports` methods. `create`/`update` open a transaction and
  call `replace_imports_tx` to populate the dep-graph.
- Admin endpoint: accepts `kind`; rejects reserved module names;
  rejects `endpoint → module` transitions when routes / triggers
  exist.
- SDK_VERSION 1.3 → 1.4.

Workspace builds; full test suite (~440 tests) green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/shared/src/services.rs

@@ -7,9 +7,11 @@
 //! handed to `executor-core::sdk::register_all` alongside an
 //! `SdkCallCx` to wire each `::` namespace.
 //!
-//! v1.1.0 shipped this empty; v1.1.1 adds the first two service fields
+//! v1.1.0 shipped this empty; v1.1.1 added the first two service fields
 //! (`kv`, `dead_letters`) plus the `events` emitter that bound services
-//! use to publish events into the triggers outbox.
+//! use to publish events into the triggers outbox. v1.1.3 adds the
+//! `modules` field — the `ModuleSource` consulted by the per-call
+//! `PicloudModuleResolver` to load `import`ed module scripts.
 //!
 //! `#[non_exhaustive]` so adding fields is a non-breaking change for
 //! consumers that only *pattern-match* a `&Services`; only crates that
@@ -18,8 +20,8 @@
 use std::sync::Arc;
 
 use crate::{
-    DeadLetterService, DocsService, KvService, NoopDeadLetterService, NoopDocsService,
-    NoopEventEmitter, NoopKvService, ServiceEventEmitter,
+    DeadLetterService, DocsService, KvService, ModuleSource, NoopDeadLetterService, NoopDocsService,
+    NoopEventEmitter, NoopKvService, NoopModuleSource, ServiceEventEmitter,
 };
 
 /// SDK service bundle. See module docs for the lifecycle and the v1.1.x
@@ -45,6 +47,12 @@ pub struct Services {
     /// `manager-core::outbox_event_emitter` replaces v1.1.0's
     /// `NoopEventEmitter`.
     pub events: Arc<dyn ServiceEventEmitter>,
+
+    /// Module source (v1.1.3). The `PicloudModuleResolver` consults
+    /// this to load `kind = 'module'` scripts that other scripts
+    /// `import`. Backed by Postgres in the picloud binary; in-memory
+    /// fakes in resolver tests.
+    pub modules: Arc<dyn ModuleSource>,
 }
 
 impl Services {
@@ -57,12 +65,14 @@ impl Services {
         docs: Arc<dyn DocsService>,
         dead_letters: Arc<dyn DeadLetterService>,
         events: Arc<dyn ServiceEventEmitter>,
+        modules: Arc<dyn ModuleSource>,
     ) -> Self {
         Self {
             kv,
             docs,
             dead_letters,
             events,
+            modules,
         }
     }
 
@@ -78,6 +88,7 @@ impl Services {
             Arc::new(NoopDocsService),
             Arc::new(NoopDeadLetterService),
             Arc::new(NoopEventEmitter),
+            Arc::new(NoopModuleSource),
         )
     }
 }