Expand deterministic test coverage

[jackgladowsky]

Summary

• extract deterministic config, scheduler, background, and Telegram command helpers for isolated testing
• add unit tests for compaction, config validation, scheduler logic, background task rendering/pipeline helpers, Telegram formatting/commands, and local STT helpers
• keep CI unchanged because it already runs all built dist/**/*.test.js files

Tests

• git diff --check origin/main...HEAD
• pnpm run typecheck
• pnpm run build
• pnpm test — 24 tests