[100%] Phase 4: Move critter-core into morphia-core

[evanchooly]

Parent: #4179
Blocked by: #4195

Goal

Physically move Java source (converted in Phase 3) into morphia-core, configure optional bytecode-generation dependencies, refactor Generators singleton to instance, update CritterClassLoader.

Details

See Phase 4 in planning doc

Tasks

• Add optional dependencies to core/pom.xml: gizmo, asm-tree, asm-util, byte-buddy, roaster-jdt (no Kotlin plugin needed)
• Move all Java source files from critter/core to core preserving package structure
• Move relevant test files from critter/core to core
• Refactor Generators from static singleton to instance class with constructor injection
• Update all files referencing Generators.config/Generators.mapper to use instance
• Update CritterClassLoader to accept parent classloader parameter
• Verify pure-Java compilation succeeds
• Run critter-core tests from new location

Progress Tracking

phase_percentage = (completed_tasks / 8) * 100, rounded to nearest integer
gh issue edit 4186 --repo MorphiaOrg/morphia --title "[XX%] Phase 4: Move critter-core into morphia-core"

parent_percentage = (total_completed_tasks_across_all_phases / 56) * 100, rounded to nearest integer
gh issue edit 4179 --repo MorphiaOrg/morphia --title "[XX%] Integrate critter-core into morphia-core"

When all tasks are complete (100%), close this issue and check its box in #4179.