Core Systems Libraries for Google Workspace API wrappers.

Provides shared credential management, data converters, and request
execution helpers used by all clj-goog-workspace-* sub-libraries.

Converters:
- ->clj       — Google API model object (GenericJson / Map / List) -> Clojure
                data with kebab-case keyword keys.
- ->camel-str — keyword/string -> camelCase string (API field/option names).
- clj->json   — Clojure map (kebab-case keywords) -> java.util.HashMap
                (camelCase string keys) for use with GenericJson.putAll.

Client construction:
- http-request-initializer — build an HttpRequestInitializer that wraps
                             GoogleCredentials with HTTP timeout
                             configuration. Used by every <service>-client
                             builder in the workspace.

Request execution:
- json-factory   — shared GsonFactory used for typed-model JSON round-trip.
- execute-get    — issue a get/patch/create request; returns {:data ...} or
                   {:error ...}.
- execute-list   — issue a list request; returns {:data [...] :next-page-token
                   "..."} or {:error ...}.
- execute-delete — issue a delete/clear (void) request; returns {:data
                   :deleted} or {:error ...}.

All three executors accept an optional opts map with :read-timeout-ms and/or
:connect-timeout-ms to apply per-request HTTP timeouts (overriding the
client-level defaults set by http-request-initializer).