feat(vars): VarsService + vars:: SDK + config capabilities

Scripts can now read group-inherited config via vars::get(key) / vars::all().

- shared: VarsService trait (read-only get/all) + NoopVarsService; added as
  the 14th field on the Services bundle.
- manager-core: VarsServiceImpl resolves the calling app's config via
  config_resolver (derives app_id from cx.app_id; AppVarsRead-gated for
  authed principals, script-as-gate for anon).
- executor-core: vars:: Rhai bridge (get/all), registered in the SDK.
- authz: AppVarsRead/Write, GroupVarsRead/Write, GroupSecretsRead/Write
  capabilities (group caps resolve via the Phase-2 ancestor walk; the
  GroupSecretsRead human-read gate is group_admin-only, distinct from an
  app's runtime injection).
- wired VarsServiceImpl into the picloud binary; updated the executor-core
  test Services::new call sites.

386 manager-core lib tests green; clippy clean.

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

crates/executor-core/src/sdk/mod.rs

@@ -26,6 +26,7 @@ pub mod retry;
 pub mod secrets;
 pub mod stdlib;
 pub mod users;
+pub mod vars;
 
 pub use bridge::{dynamic_to_json, json_to_dynamic};
 pub use cx::SdkCallCx;
@@ -62,6 +63,7 @@ pub fn register_all(
     queue::register(engine, services, cx.clone());
     retry::register(engine, services, cx.clone());
     secrets::register(engine, services, cx.clone());
+    vars::register(engine, services, cx.clone());
     email::register(engine, services, cx.clone());
     users::register(engine, services, cx.clone());
     invoke::register(engine, services, cx, limits, self_engine);

crates/executor-core/src/sdk/vars.rs

@@ -0,0 +1,57 @@
+//! `vars::` Rhai bridge — read-only access to the app's resolved,
+//! group-inherited config (Phase 3).
+//!
+//! ```rhai
+//! let region = vars::get("region");   // value or ()
+//! let all = vars::all();              // #{ key: value, ... }
+//! ```
+//!
+//! Values are inherited down the group tree and env-filtered (§3); the
+//! resolution happens server-side in manager-core. Writes go through the
+//! admin API, not the SDK. `app_id` is derived from `cx.app_id` in the
+//! service — never a script argument — preserving cross-app isolation.
+
+use std::sync::Arc;
+
+use picloud_shared::{SdkCallCx, Services};
+use rhai::{Dynamic, Engine as RhaiEngine, EvalAltResult, Map, Module};
+
+use super::bridge::{block_on, json_to_dynamic};
+
+pub(super) fn register(engine: &mut RhaiEngine, services: &Services, cx: Arc<SdkCallCx>) {
+    let svc = services.vars.clone();
+    let mut module = Module::new();
+
+    // vars::get(key) — resolved value, or () if no level defines it.
+    {
+        let svc = svc.clone();
+        let cx = cx.clone();
+        module.set_native_fn(
+            "get",
+            move |key: &str| -> Result<Dynamic, Box<EvalAltResult>> {
+                let svc = svc.clone();
+                let cx = cx.clone();
+                let opt = block_on("vars", async move { svc.get(&cx, key).await })?;
+                Ok(opt.map_or(Dynamic::UNIT, json_to_dynamic))
+            },
+        );
+    }
+
+    // vars::all() — the fully-resolved config map.
+    {
+        let svc = svc.clone();
+        let cx = cx.clone();
+        module.set_native_fn("all", move || -> Result<Map, Box<EvalAltResult>> {
+            let svc = svc.clone();
+            let cx = cx.clone();
+            let resolved = block_on("vars", async move { svc.all(&cx).await })?;
+            let mut m = Map::new();
+            for (k, v) in resolved {
+                m.insert(k.into(), json_to_dynamic(v));
+            }
+            Ok(m)
+        });
+    }
+
+    engine.register_static_module("vars", module.into());
+}