Fix: Correct precompile_hook detection to use top-level config key

The master's sophisticated hook detection was looking for the hook at
`:hooks/:precompile` but shakapacker.yml uses `precompile_hook` at the
top level. Updated `extract_precompile_hook` to look in the correct
location.

Also updated specs to match the sophisticated implementation that checks
if the hook actually contains the generate_packs rake task, rather than
just checking for any hook presence.

Fixes failing rspec-package-tests in CI.

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

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

Author: justin808

lib/react_on_rails/packer_utils.rb

@@ -197,8 +197,8 @@ def self.extract_precompile_hook
       config_data = ::Shakapacker.config.send(:data)
 
       # Try symbol keys first (Shakapacker's internal format), then fall back to string keys
-      # Note: Currently only one hook value is supported, but this will change to support lists
-      config_data&.dig(:hooks, :precompile) || config_data&.dig("hooks", "precompile")
+      # The key is 'precompile_hook' at the top level of the config
+      config_data&.[](:precompile_hook) || config_data&.[]("precompile_hook")
     end
 
     def self.hook_contains_generate_packs?(hook_value)

spec/react_on_rails/packer_utils_spec.rb

@@ -148,10 +148,18 @@ module ReactOnRails
       end
 
       context "when precompile_hook is configured" do
-        it "returns true" do
-          allow(mock_config).to receive(:send).with(:data).and_return({ precompile_hook: "bin/hook" })
+        it "returns true when hook command contains generate_packs rake task" do
+          hook_value = "bundle exec rake react_on_rails:generate_packs"
+          allow(mock_config).to receive(:send).with(:data)
+                                              .and_return({ precompile_hook: hook_value })
           expect(described_class.shakapacker_precompile_hook_configured?).to be true
         end
+
+        it "returns false when hook command doesn't contain generate_packs" do
+          allow(mock_config).to receive(:send).with(:data)
+                                              .and_return({ precompile_hook: "bin/some-other-command" })
+          expect(described_class.shakapacker_precompile_hook_configured?).to be false
+        end
       end
 
       context "when precompile_hook is not configured" do