feat: standardizes logging across the Notify-Chain listener service for easier debugging and monitoring. All production code now uses the centralized Winston logger with consistent structure, log levels, timestamps, and error formatting.

[miss-yusrah]

Summary

Standardizes logging across the Notify-Chain listener service for easier debugging and monitoring. All production code now uses the centralized Winston logger with consistent structure, log levels, timestamps, and error formatting.

closes #9

Changes

Logger utility (listener/src/utils/logger.ts)

• Added formatError() helper that normalizes errors into structured objects (message, name, stack, cause)
• All error metadata fields are automatically formatted before logging
• Exposed debug, info, warn, and error levels with consistent metadata handling
• Timestamps remain ISO 8601 via Winston; dev output is colorized, production output is newline-delimited JSON

Service logging consistency

• Discord notifications: Removed duplicate "Discord notification sent successfully" log; single "Discord notification delivered" entry with full context
• Notification scheduler: Added requestId per poll batch, durationMs on batch/notification operations, and debug-level empty poll cycle logs
• Scheduled notification repository & API: Thread optional requestId through create/schedule/cancel operations
• Events API: Passes requestId into scheduling calls for end-to-end traceability
• Event registry: Emits warn when evicting oldest events at capacity

Scripts & configuration

• Replaced all console.log / console.error in example scripts with structured logger calls
• Added LOG_LEVEL=info to listener/.env.example
• Synced listener/package-lock.json with existing sqlite3 and uuid dependencies

Documentation & tests

• Updated listener/LOGGING.md with scheduler lifecycle events, registry warnings, and error formatting guidance
• Added listener/src/utils/logger.test.ts for formatError()
• Updated event-registry.test.ts to verify capacity eviction warnings

CI fix

• Applied cargo fmt to contract/contracts/hello-world/src/autoshare_logic.rs (pre-existing formatting drift that would fail the Rust fmt check)

Acceptance criteria

• Logging is consistent throughout the listener project (Winston + structured metadata everywhere)
• Log levels are used appropriately (debug, info, warn, error)
• Timestamps included on every log entry (Winston timestamp() format)
• Errors contain useful debugging information (message, name, stack, optional cause)

Test plan

• cd listener && npm run build — TypeScript compiles cleanly
• cd listener && npx jest src/utils/logger.test.ts src/store/event-registry.test.ts src/services/discord-notification.test.ts — new and affected tests pass
• cd dashboard && npm run lint && npm run build && npm test — CI frontend job passes
• cd contract && cargo fmt --all -- --check && cargo test --workspace --all-features — CI Rust job passes
• Manual: run listener with LOG_LEVEL=debug and confirm scheduler poll cycles appear
• Manual: trigger a Discord webhook failure and confirm structured error output includes stack trace

Configuration

# listener/.env
LOG_LEVEL=info        # debug | info | warn | error
# NODE_ENV=production # uncomment for JSON log output