Admit captured property writes to production bytecode

[rogeralsing]

Summary

• admit simple-return named and computed property writes from captured ordinary dynamic identifier bases
• thread dynamic identifier admission through first-boundary property-set eligibility/compiler helpers without adding fallback execution
• add eligibility and public route-hit coverage for captured arrow and ordinary closure property write expressions
• update the unified bytecode expansion contract to describe the new captured property write boundary

Proof

• rtk dotnet test tests/Asynkron.JsEngine.Tests --filter "FullyQualifiedNameEvaluate_NamedPropertyWriteWithDynamicIdentifierBase_AcceptsWhenDynamicReadsAreAdmitted|FullyQualifiedNameEvaluate_ComputedPropertyWriteWithDynamicIdentifierBase_AcceptsWhenDynamicReadsAreAdmitted|FullyQualifiedNameArrowFunction_CapturedPropertyWriteExpression_UsesUnifiedBytecodeProductionFastPath|FullyQualifiedNameFunctionExpression_CapturedPropertyWriteExpression_UsesUnifiedBytecodeProductionFastPath|FullyQualifiedNameArrowFunction_CapturedComputedPropertyWriteExpression_UsesUnifiedBytecodeProductionFastPath|FullyQualifiedNameFunctionExpression_CapturedComputedPropertyWriteExpression_UsesUnifiedBytecodeProductionFastPath"
• rtk dotnet test tests/Asynkron.JsEngine.Tests --filter "FullyQualifiedName~UnifiedBytecodeProductionEligibilityTests"
• rtk dotnet test tests/Asynkron.JsEngine.Tests --filter "FullyQualifiedName~UnifiedBytecodeProductionInvocationTests"
• rtk dotnet test tests/Asynkron.JsEngine.Tests --filter "FullyQualifiedName~UnifiedBytecodeProduction"
• rtk dotnet test tests/Asynkron.JsEngine.Tests --filter "FullyQualifiedName~ActivationSemanticsProofPackTests"
• rtk dotnet build -c Release
• rtk rg "EvaluateExpression\(|ProfileEvaluateExpression\(" src/Asynkron.JsEngine/Ast/TypedAstEvaluator.ExecutionPlanRunner* (no matches)
• rtk ./tools/profile forloop --memory (6.86 MB)
• rtk git diff --check

[Copilot]

Pull request overview

This PR expands the unified bytecode “production” fast-path to admit additional first-boundary property-write shapes where the assignment base is a captured ordinary dynamic identifier (in the same spirit as the existing dynamic-base property-read admission). It threads dynamic-identifier admission through the production eligibility checks and the compiler helpers (without introducing mixed/fallback execution), and adds targeted tests plus contract documentation updates.

Changes:

• Extend production eligibility to treat first-boundary named/computed property writes as eligible when the base is an admitted ordinary dynamic identifier read.
• Update unified bytecode compilation helpers to emit LoadDynamicIdentifier for eligible simple operands in first-boundary property-set shapes (including computed-key spans).
• Add eligibility and invocation tests covering captured property-write expressions for both arrow and ordinary closures, and update the unified bytecode expansion contract.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionInvocationTests.cs	Adds invocation-level coverage that captured property-write expressions route through the unified-bytecode production fast-path.
tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionEligibilityTests.cs	Adds eligibility coverage asserting dynamic-identifier-base property writes are accepted when ordinary dynamic reads are admitted.
src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeProductionEligibility.cs	Widens first-boundary property-write candidacy to accept activation-resolved or admitted plain dynamic-identifier base reads.
src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeCompiler.cs	Threads allowsDynamicIdentifiers through first-boundary property-set compilation and computed-key span support, enabling LoadDynamicIdentifier emission where eligible.
docs/unified-bytecode-expansion-contract.md	Updates the contract to describe the newly admitted captured dynamic-base property-write boundary.

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