Replace Rhino JS engine with QuickJS4J (WebAssembly-based)

[andreaTP]

Replace Mozilla Rhino with QuickJS4J (QuickJS compiled to WebAssembly via Chicory), providing a naturally sandboxed JS execution environment without the need for custom AST validation or sandbox wrappers.

Key changes:

• Add quickjs4j dependencies and annotation processor
• Remove Rhino dependency and all sandbox infrastructure (SandboxContextFactory, SandboxWrapFactory, SandboxNativeJavaObject/List/Map, ScriptValidation, JSNodeVisitor, JSSymbol, JSErrorReporter, JSON)
• Create annotated @builtins API classes (SimpleHttpClientApi, ExtensionUtilsApi, LogApi, ConsoleApi, ExtensionLoggerApi, InternalApi) for type-safe host bindings
• Rewrite ScriptingExecutionService to use Engine/Runner with generated Builtins
• Switch serialization from GSON to Jackson (Json.OBJECT_MAPPER) throughout
• Add JS_PRELUDE shims for backward compatibility (HashMap, GSON, variadic wrappers for console/log/ExtensionUtils.format/computeHMAC)
• Rewrite bundled mailchimp.js and sample.js for pure JS compatibility (no Java.type, no method calls on serialized objects)
• Fix test scripts for QuickJS strict mode (var declarations, JSON.parse)

All 815 tests pass.

[codecov]

Codecov Report

❌ Patch coverage is 51.63934% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.13%. Comparing base (1df2075) to head (e0e6a18).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...main/java/alfio/extension/SimpleHttpClientApi.java	7.89%	35 Missing ⚠️
...ava/alfio/extension/ScriptingExecutionService.java	82.00%	5 Missing and 4 partials ⚠️
...c/main/java/alfio/extension/ExtensionUtilsApi.java	33.33%	6 Missing ⚠️
src/main/java/alfio/extension/LogApi.java	42.85%	4 Missing ⚠️
.../main/java/alfio/extension/ExtensionLoggerApi.java	50.00%	3 Missing ⚠️
src/main/java/alfio/extension/ConsoleApi.java	80.00%	1 Missing ⚠️
...java/alfio/extension/SimpleHttpClientResponse.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1512      +/-   ##
============================================
- Coverage     58.23%   58.13%   -0.10%     
+ Complexity     4579     4542      -37     
============================================
  Files           598      592       -6     
  Lines         23741    23630     -111     
  Branches       2122     2092      -30     
============================================
- Hits          13825    13738      -87     
+ Misses         8622     8602      -20     
+ Partials       1294     1290       -4     

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