Prepare ClassicSpeech 2.0 release notes and updater clarification

[trssharp]

Summary

• Consolidate all merged PRs ClassicSpeech 1.02: latency fix, edit fields, Mouse voice, Speech and Sound Schemes #16 through Correct obvious Spanish translation errors found in catalog audit #39 into the 2.0 release notes and synchronize the manifest changelog.
• Fix manual update checks when the installed build is newer than the published release; clarify the user guide and update Spanish catalogs.
• Select RELEASE-2.0.md for packaging and keep the README latest-release link current.

Verification

• 752 tests across 32 harnesses passed locally, with no skips.
• Regression reproduced the misleading message before the fix.
• Tim confirmed the corrected updater works in live NVDA.
• Package contents, changelog, HTML nesting, and checksum verified.

Release boundary

Prepare a verified draft only. Do not publish 2.0 as part of this PR.