feat(keymap): SDK 1.7 keyboard remapping and v1.8.1-beta.1

[SoftBlack42]

Summary

• Add SDK 1.7 host-managed keyboard remapping and visual KeyMap editor.
• Fix false required-parameter warning for valid mappings; preserve validation for missing or invalid mappings.
• Prepare v1.8.1-beta.1 release metadata and installer fallback versions.

Verification

• Release build: 0 warnings, 0 errors.
• Isolated --plugin-selftest --skip-invoke: PASS, including valid/missing/invalid/dynamic parameter UI states.
• Human live acceptance: passed by project owner.
• Official KeypadLayer module will be published separately after this host release.

Only source and release metadata are committed; local scratch test artifacts are excluded.