perf(swift): optimize swift serialization performance - #3921

Why?

Swift's dynamic exclusivity checks and generic collection/String paths add measurable overhead to
serialization and deserialization, especially for small structs and collection-heavy objects.

What does this PR do?

• Removes dynamic exclusivity checks from synchronous ByteBuffer state access.
• Specializes packed primitive-array reads and avoids zero-initializing destination arrays.
• Accelerates ASCII String detection with eight-byte checks while preserving UTF-8 validation.
• Adds a direct fast path for non-null Array elements.
• Uses the TypeMeta header hash directly for exact-schema compatible reads.
• Refreshes the Swift benchmark report and throughput plot.

Related issues

Closes #3460

AI Contribution Checklist

• Substantial AI assistance was used in this PR: yes / no
• If yes, I included a completed AI Contribution Checklist in this PR description and the required AI Usage Disclosure.
• If yes, my PR description includes the required ai_review summary and screenshot evidence or equivalent persisted links of the final clean AI review results from both fresh reviewers described in AI_POLICY.md, the Fory-guided reviewer and the independent general reviewer, on the current PR diff or current HEAD after the latest code changes.

Does this PR introduce any user-facing change?

• Does this PR introduce any public API change?
• Does this PR introduce any binary protocol compatibility change?

Benchmark

Environment: Apple Swift 6.2.1. The complete benchmark used three seconds per case:

cd benchmarks/swift
./run.sh