Finalize PLT dynamic tags for self linker

[katsyoshi]

Goal

Finalize and validate PLT-related dynamic tags emitted by the self linker.

Scope

• Ensure points to
• Ensure is set to
• Ensure matches size
• Ensure points to
• Verify consistency between , section headers, and relocation tables

Acceptance Criteria

• shows coherent PLT dynamic tags
• shows entries resolved without symbol-index warnings
• Existing linker tests remain green