fix(macro)!: consistent getter/setter property naming and order

[ptondereau]

Description

Getter/setter properties now follow the field naming rule (camelCase, name/change_case honoured), are declared in source order, and conflicting getter/setter declarations or a field/method name collision are errors instead of silent picks. PropertyDescriptor::mangled_name is gone: every mangled name is computed at runtime, which fixes get_properties for non-literal flags expressions.

Checklist

• I have read the contribution guidelines and the code of conduct.
• I have added tests that prove my code works as expected.
• I have added documentation if applicable.
• I have added a migration guide if applicable.

[coveralls]

Coverage Report for CI Build 35575985860

Coverage increased (+0.1%) to 69.553%

Details

• Coverage increased (+0.1%) from the base build.
• Patch coverage: 15 uncovered changes across 4 files (88 of 103 lines covered, 85.44%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
crates/macros/src/impl_.rs	59	54	91.53%
src/class.rs	4	0	0.0%
src/builders/class.rs	37	34	91.89%
src/zend/handlers.rs	3	0	0.0%

Coverage Regressions

No coverage regressions found.

---

Coverage Stats

Relevant Lines:	13952
Covered Lines:	9704
Line Coverage:	69.55%
Coverage Strength:	52.66 hits per line

---

💛 - Coveralls

[codspeed]

Merging this PR will not alter performance

✅ 30 untouched benchmarks

---

_{Comparing fix/dx1b-property-naming-order (684c955) with master (a25eb73)}