TTS: release v2.0 — version bump, changelog, build + notarize

[thefourcraft]

Part of the Read Aloud (TTS) epic. Final step.

Scope

• Bump MARKETING_VERSION 1.0.0 -> 2.0.0 (+ build number).
• Changelog / appcast entry for Read Aloud.
• xcodebuild release build; sign (Developer ID, Hardened Runtime), notarize + staple.

Known blockers (from release-readiness notes): notary issuer ID + missing Sparkle EdDSA signing key must be resolved before a public Sparkle update can ship. Flag if unresolved.

Acceptance: notarized build of 2.0.0 with Read Aloud working end-to-end.

[thefourcraft]

Closing as completed. Read Aloud shipped in the 2.x line (current published baseline is 2.8.2). Future signing/notarization stays on the release-identity ticket.