Bump plumcp to 0.2.0-beta3, remove upstream-fixed workarounds

- Remove flushing-stdio-transport wrapper (flush bug fixed in beta3)
- Replace manual initialized? atom with wrap-initialized-check
- Exclude plumcp .cljc sources from uberjar to fix AOT classloader bug
  where DynamicClassLoader re-evaluates defprotocol, creating incompatible
  interface classes vs AppClassLoader-loaded AOT reify classes

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca <noreply@eca.dev>

Author: ericdallo

build.clj

@@ -33,10 +33,16 @@
                     :src-dirs src-dirs
                     :java-opts ["-server"]
                     :class-dir class-dir})
+    ;; Remove plumcp protocol source from the uberjar. When both .cljc source
+    ;; and .class files coexist, Clojure may re-evaluate defprotocol from
+    ;; source under DynamicClassLoader, creating a new interface class that's
+    ;; incompatible with AOT-compiled reify classes loaded by AppClassLoader
+    ;; (different classloaders = different classes).
     (b/uber {:class-dir class-dir
              :uber-file file
              :main 'eca.main
-             :basis basis})))
+             :basis basis
+             :exclude ["plumcp/.*\\.cljc"]})))
 
 (defn ^:private bin
   "Create an executable `eca` script out of UBER-FILE jar with