chore: drop hard dependency on Puma as web server

Gemfile.lock

@@ -4,7 +4,6 @@ PATH
     kirei (0.6.2)
       oj (~> 3.0)
       pg (~> 1.0)
-      puma (~> 6.0)
       rack (~> 3.0)
       sequel (~> 5.0)
       sequel_pg (~> 1.0)
@@ -27,7 +26,6 @@ GEM
     json (2.7.2)
     language_server-protocol (3.17.0.3)
     netrc (0.11.0)
-    nio4r (2.7.3)
     oj (3.16.3)
       bigdecimal (>= 3.0)
     parallel (1.24.0)
@@ -36,8 +34,6 @@ GEM
       racc
     pg (1.5.6)
     prism (0.29.0)
-    puma (6.4.3)
-      nio4r (~> 2.0)
     racc (1.7.3)
     rack (3.0.11)
     rainbow (3.1.1)

kirei.gemspec

@@ -51,7 +51,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency "zeitwerk", "~> 2.5"
 
   # Web server & routing
-  spec.add_dependency "puma", "~> 6.0"
   spec.add_dependency "rack", "~> 3.0"
 
   # Database (Postgres)

lib/kirei/routing/rack_env_type.rb

@@ -4,20 +4,24 @@
 module Kirei
   module Routing
     RackEnvType = T.type_alias do
-      T::Hash[
-        String,
-        T.any(
-          T::Array[T.untyped],
-          IO,
-          T::Boolean,
-          String,
-          Numeric,
-          TCPSocket,
-          ::Puma::Client,
-          StringIO,
-          ::Puma::Configuration,
-        )
-      ]
+      #
+      # in plain rack, the value could be any of:
+      #
+      #   T::Array[T.untyped]
+      #   IO
+      #   T::Boolean
+      #   String
+      #   Numeric
+      #   TCPSocket
+      #   StringIO
+      #
+      # The web server (e.g. Puma) might alter this to e.g.
+      #   ::Puma::Client
+      #   ::Puma::Configuration
+      #
+      # Thus we leave it as T.untyped.
+      #
+      T::Hash[String, T.untyped]
     end
   end
 end