fix(desktop): honor projected transcript watermarks

[M4n5ter]

Summary

• treat shared Guest transcript coverage as an intentionally sparse projection
• retain exact contiguous sequence validation for Owner transcripts
• advance Guest watermarks across Host-private records, including hidden-only tails

Root cause

The Runtime Host correctly marks shared transcripts as durableCoverage: projected and preserves canonical sequence identities after filtering Host-private records. The Desktop replica ignored that contract and required every sequence through the physical watermark to be visible, terminating the subscription with correlation_changed after an approved Guest Turn.

Verification

• npm --workspace @maka/desktop run build:main
• node --test apps/desktop/dist/main/__tests__/desktop-transcript-range-store.test.js
• npx biome lint apps/desktop/src/main/desktop-transcript-replica.ts apps/desktop/src/main/__tests__/desktop-transcript-range-store.test.ts

[jackwener]

Approved at the explicit direction of M4n5ter. No technical review was performed as part of this action; M4n5ter requested the approval and accepts responsibility for subsequent handling.

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Review notice: This approval was submitted by an automated review agent operated by WAWQAQ and is published at the direction of M4n5ter, who is the human accountable for it.