chore: add .mise.toml and explicit csv/logger dependencies

Ruby 3.4+ removed csv and logger from default gems, requiring
them as explicit dependencies. Also add .mise.toml to pin Ruby 3
for the project.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.mise.toml

@@ -0,0 +1,2 @@
+[tools]
+ruby = "3"

Gemfile

@@ -2,7 +2,9 @@
 
 source 'https://rubygems.org/'
 
+gem 'csv'
 gem 'github-pages'
+gem 'logger'
 
 group :development do
   gem 'rake'

Gemfile.lock

@@ -24,6 +24,7 @@ GEM
     commonmarker (0.23.10)
     concurrent-ruby (1.2.3)
     connection_pool (2.4.1)
+    csv (3.3.5)
     dnsruby (1.72.1)
       simpleidn (~> 0.2.1)
     drb (2.2.1)
@@ -216,6 +217,7 @@ GEM
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
+    logger (1.7.0)
     mercenary (0.3.6)
     mini_portile2 (2.8.6)
     minima (2.5.1)
@@ -290,7 +292,9 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  csv
   github-pages
+  logger
   rake
   rubocop
   webrick