fix: report telegram ask provenance

[TerrifiedBug]

Summary

• prefix every telegram_ask result with machine-readable posted-surface and answer-origin provenance
• preserve loud per-surface errors when Telegram posting fails but a terminal answer succeeds
• track Telegram posting at the Bot API boundary without changing first-answer routing or cancellation semantics
• document the result contract and pin terminal-only, both dual-surface answer origins, and partial-delivery failure

Verification

• bun install
• bun run check (273 tests pass)

Closes #50