refactor: remove envresolve, pass app env vars directly

The template resolution logic (needsShared/needsSiblings scanning,
shared var fetching, sibling var fetching) adds unnecessary complexity.
Just pass app env vars straight through as secrets.

Author: Flo4604

svc/ctrl/internal/envresolve/BUILD.bazel

@@ -19,7 +19,6 @@ go_library(
         "//pkg/db",
         "//pkg/logger",
         "//pkg/uid",
-        "//svc/ctrl/internal/envresolve",
         "@com_connectrpc_connect//:connect",
         "@com_github_restatedev_sdk_go//ingress",
         "@org_golang_google_protobuf//encoding/protojson",