Update react_on_rails to use master branch from GitHub

Switch from using the published beta.12 gem to using the tip of master branch
from the shakacode/react_on_rails GitHub repository.

This ensures we have the latest fixes and improvements from the master branch,
including any recent updates beyond beta.12.

- Change Gemfile to point to GitHub master branch
- Update Gemfile.lock to use commit 2306825e09d761a88fdd20960e5d5072bc753293
- npm package remains at 16.2.0-beta.12 (matching gem version)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

Gemfile.lock

@@ -1,3 +1,16 @@
+GIT
+  remote: https://github.com/shakacode/react_on_rails.git
+  revision: 2306825e09d761a88fdd20960e5d5072bc753293
+  branch: master
+  specs:
+    react_on_rails (16.2.0.beta.12)
+      addressable
+      connection_pool
+      execjs (~> 2.5)
+      rails (>= 5.2)
+      rainbow (~> 3.0)
+      shakapacker (>= 6.0)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -293,13 +306,6 @@ GEM
       erb
       psych (>= 4.0.0)
       tsort
-    react_on_rails (16.2.0.beta.12)
-      addressable
-      connection_pool
-      execjs (~> 2.5)
-      rails (>= 5.2)
-      rainbow (~> 3.0)
-      shakapacker (>= 6.0)
     redcarpet (3.6.0)
     redis (5.3.0)
       redis-client (>= 0.22.0)
@@ -483,7 +489,7 @@ DEPENDENCIES
   rails-html-sanitizer
   rails_best_practices
   rainbow
-  react_on_rails (= 16.2.0.beta.12)
+  react_on_rails!
   redcarpet
   redis (~> 5.0)
   rspec-rails (~> 6.0.0)