feat(v1.1.2-docs): Rhai docs:: SDK module + ctx.event.docs + bridge tests

The docs:: SDK bridge mirrors kv::'s collection-handle pattern: a
custom Rhai type DocsHandle captures (collection, service, cx) once
via docs::collection(name), and methods bind via engine.register_fn
so scripts use dot-notation (users.create(...), users.find(...),
etc.). app_id never appears in the script-visible call shape — the
service derives it from cx.app_id, preserving cross-app isolation.

Methods registered: create, get, find, find_one, update, delete,
list (zero-arg and one-arg map-shaped overloads). The find filter
goes through dynamic_to_json -> DocsService::find -> docs_filter
parser; unsupported operators surface to Rhai with the parser's
verbatim error message (including the v1.2 pointer).

The doc envelope per Decision D:
  #{ id: "uuid", data: #{...user data...},
     created_at: "ISO-8601", updated_at: "ISO-8601" }

engine.rs trigger_event_to_dynamic gains a Docs arm that builds
ctx.event.docs = #{ collection, id, data, prev_data } where data
and prev_data follow the variant's Option<Value> -> () | map shape.

15 bridge integration tests under tests/sdk_docs.rs exercise the
round-trip via tokio::task::spawn_blocking. Covers create/get/find/
find_one/update/delete/list semantics, $in + $gt operators, the
unsupported-operator throw with v1.2 pointer, invalid-UUID rejection
on get/update/delete, the doc envelope's shape (id is string, data
is map, timestamps are strings), and the load-bearing cross-app
isolation guarantee. sdk_kv.rs is updated to take the new docs
field on Services::new.

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

crates/executor-core/tests/sdk_kv.rs

@@ -10,8 +10,8 @@ use std::sync::Arc;
 use async_trait::async_trait;
 use picloud_executor_core::{Engine, ExecRequest, InvocationType, Limits};
 use picloud_shared::{
-    AppId, ExecutionId, KvError, KvListPage, KvService, NoopDeadLetterService, NoopEventEmitter,
-    RequestId, ScriptId, ScriptSandbox, SdkCallCx, Services,
+    AppId, ExecutionId, KvError, KvListPage, KvService, NoopDeadLetterService, NoopDocsService,
+    NoopEventEmitter, RequestId, ScriptId, ScriptSandbox, SdkCallCx, Services,
 };
 use serde_json::{json, Value};
 use tokio::sync::Mutex;
@@ -101,6 +101,7 @@ impl KvService for InMemoryKv {
 fn make_engine() -> Arc<Engine> {
     let services = Services::new(
         Arc::new(InMemoryKv::default()),
+        Arc::new(NoopDocsService),
         Arc::new(NoopDeadLetterService),
         Arc::new(NoopEventEmitter),
     );