✨[Feat] Refine metadata inspection and cleaning - #51

Summary

• unify Image and PDF Metadata source-card UX with accessible reset paths
• make decoded metadata primary with native progressive disclosure
• keep Privacy Clean as the default and add supported class-level customization
• fail closed when requested metadata remains after verification
• add six-locale copy, responsive contracts, regression coverage, and QA documentation

Validation

• git diff --check
• node tests/run-all.mjs
• Browser QA attempted but blocked before navigation by the Windows ACL sandbox failure documented in the v2 QA gate

Closes #45
Closes #46
Closes #47
Closes #48
Closes #49
Closes #50