Unify messaging delivery and native chat history

[fmhall]

Replying to an older iMessage now supplies its message ID and part index in durable history. Reactions use an explicit target, one validated Unicode emoji, and an add/remove operation.

All messaging tools share one awaited delivery function. It checks the authenticated destination, validates reaction conversation membership, preserves scoped private images and reply fallback, and uses stable tool-call, contact, or scheduled-report delivery keys. Provider errors fail the tool; channel callbacks retain inbound/authentication and lifecycle handling without posting completed messaging-tool results again.

The browser transcript is projected once from ordered Eve events, preserving overlapping-input order, quoted-part previews, targeted reactions, attachments, and literal annotation text. Full trace uses Eve's reduced messages. The separate delivery map, presentation map, suppression set, and content-override prop are removed. The ingress formatter and UI parser share their annotation contract.

Validation:

• pnpm check: six tasks passed; 956 tests across 100 files.
• pnpm build: passed.
• pnpm test:runtime: two cases and 13 gates passed.
• Real-model reaction/history evals: five cases and 33 gates passed in the final run. The pre-cleanup baseline missed the quoted-reaction case; the passing final sample does not establish causality.
• Local Chrome desktop/mobile testing with structured history fixtures in the production UI: history loading, quoted second image, reaction add/remove, legacy/custom emoji, delivered messages, literal annotations with uploads, trace metadata, thumbnail loading, and layout passed. Temporary fixture removed and task services stopped.
• Independent review and one fresh re-review: clean after restoring the awaited browser scheduled-report finalization regression.

The cleanup removes 276 lines of application code from the previous PR revision. Live Linq phone delivery remains unverified.