chore: Structured JSON logging with configurable log levels

[dotunv]

Overview

Add structured JSON logging with configurable log levels across the API and worker processes, replacing any ad-hoc console output.

Motivation

Production debugging requires structured, filterable logs. Currently the API and worker processes use inconsistent logging — some use fmt.Println, some use logrus. Structured JSON logs enable better integration with log aggregation tools like Datadog, Grafana Loki, or ELK.

Proposed Design

1. Adopt a single structured logger (zerolog or slog) across both cmd/api and cmd/worker
2. All log entries include: timestamp, level, message, request_id, tenant_id, operation
3. Log levels configurable via LOG_LEVEL environment variable (debug, info, warn, error)
4. HTTP request logging middleware adds request_id to all request-scoped logs
5. Error logs include stack traces at debug level
6. Sensitive fields (API keys, wallet secrets) are automatically redacted

Acceptance Criteria

• All HTTP requests are logged with method, path, status, duration, and request_id
• Worker jobs are logged with job type, duration, and success/failure status
• Log level is configurable via LOG_LEVEL env var (default: info)
• Sensitive fields are redacted in logs (API keys, secrets, mnemonics)
• Log output is valid JSON
• No sensitive data appears in any log output
• Tests verify log redaction and structured output format

[Stephan-Thomas]

@Stephan-Thomas has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

hi, i would like to work on this.

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[devgbmuyiwa]

@devgbmuyiwa has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

hello can i work on this issue

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[ghubmixxer]

@ghubmixxer has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello, please assign this to me.

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[Danielkallala]

@Danielkallala has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello,
Thank you for the opportunity to review this issue . After carefully going through the requirements, I am confident that this task is an excellent match for my expertise and experience. I have successfully completed similar projects in the past and am fully prepared to deliver high-quality results that meet your expectations.

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[TheShnider]

@TheShnider has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi. I have reviewed this issue and would like to work on it.

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[Jamixy]

@Jamixy has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello maintainer I would like to work on this issue, Thank you

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