[codex-analytics] refactor analytics to use reducer architecture (#16225)

- rework codex analytics crate to use reducer / publish architecture
- in anticipation of extensive codex analytics

codex-rs/Cargo.lock

@@ -1337,6 +1337,7 @@ checksum = "e9b18233253483ce2f65329a24072ec414db782531bdbb7d0bbc4bd2ce6b7e21"
 name = "codex-analytics"
 version = "0.0.0"
 dependencies = [
+ "codex-app-server-protocol",
  "codex-git-utils",
  "codex-login",
  "codex-plugin",