fix(runtime): expose prototype for class expression values

[TheHypnoo]

Summary

• Expose a live declared-class prototype object for heap class-expression values (ClassExprFresh) when reading .prototype.
• Wire Object.defineProperty(ClassExprFresh.prototype, ...) through the same prototype-method side tables used by class-ref prototype writes so instances observe decorator/mixin method updates.
• Extend node-suite/object/class-prototype-object with getter-capture and method-capture class-expression coverage.
• Update the NestJS fixture wall document: compat(nestjs): .prototype of a capturing class expression is undefined — tslib __decorate crashes @nestjs/common module init #4949 is resolved, and the fixture now reaches the next decorator descriptor/value wall.

Related issue

Fixes #4949

Test plan

• cargo build --release -p perry-runtime -p perry-stdlib -p perry
• ./run_parity_tests.sh --suite node-suite --module object --filter class-prototype
• ./run_parity_tests.sh --suite node-suite --module object (completed with three pre-existing object-suite mismatches: assign-descriptor-toobject, primitive-wrapper-toobject, reflect-proxy-construct)
• PERRY_BIN=../../../../target/release/perry ./fixture.sh from tests/release/packages/nestjs-hello (passes the old .prototype === undefined wall and now stops at Cannot read properties of undefined (reading 'value'))

Notes

cargo fmt --all -- --check currently reports unrelated formatting diffs in existing fetch/header files that this PR does not touch.