Add comprehensive developer documentation for banking application

[devin-ai-integration]

Add comprehensive developer documentation for banking application

Summary

This PR adds extensive developer documentation covering all 9 requested areas for both the React frontend (bank-client) and NestJS backend (bank-server) repositories. The documentation focuses heavily on banking domain knowledge, security considerations, and compliance requirements.

Documentation Added (18 files total):

For Both Repositories:

• Enhanced README.md - Detailed setup instructions, technology stack, prerequisites, and project overview
• CODING_STANDARDS.md - Development guidelines, TypeScript/React/NestJS patterns, and banking-specific coding practices
• TROUBLESHOOTING.md - Common development issues, banking-specific problems, and detailed solutions
• CONTRIBUTING.md - Code review process, branch naming, commit standards, and banking compliance guidelines
• DEVELOPMENT_WORKFLOW.md - Git branching strategy, testing requirements, deployment pipeline, and security workflows
• ENVIRONMENT_SETUP.md - Local/staging/production environment configuration with banking security principles
• DEBUGGING.md - Banking-specific debugging procedures, transaction processing, and security debugging
• TESTING.md - Testing strategies, coverage requirements (98% frontend, 90% backend), and banking test scenarios
• ONBOARDING.md - New developer guide with banking domain knowledge and security training
• .github/pull_request_template.md - PR templates with banking-specific review checklists

The documentation emphasizes banking-grade security, financial precision using Decimal.js, double-entry bookkeeping principles, multi-currency support, and regulatory compliance (PCI DSS, GDPR, AML, KYC).

Review & Testing Checklist for Human

• Verify banking domain accuracy - Review double-entry bookkeeping explanations, financial calculation examples, and regulatory compliance content for technical accuracy
• Test setup instructions end-to-end - Follow the README setup steps on a fresh environment to ensure all installation commands and configurations work correctly
• Validate code examples and configurations - Check that all code snippets, environment variables, and configuration examples match the current codebase state
• Review coverage of all 9 requested areas - Confirm that setup guides, coding standards, troubleshooting, contribution guidelines, development workflow, environment setup, debugging guides, testing procedures, and onboarding documentation are comprehensive
• Check consistency across documentation - Ensure consistent formatting, tone, and technical accuracy across all 18 documentation files

Recommended Test Plan:

1. Set up a fresh development environment following the new README instructions
2. Run through the development workflow from branch creation to PR submission
3. Test the troubleshooting solutions against real development issues
4. Verify that the testing procedures produce the expected coverage results

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    subgraph BankClient["bank-client Repository"]
        ClientREADME["README.md"]:::major-edit
        ClientCoding["CODING_STANDARDS.md"]:::major-edit
        ClientTrouble["TROUBLESHOOTING.md"]:::major-edit
        ClientContrib["CONTRIBUTING.md"]:::major-edit
        ClientWorkflow["DEVELOPMENT_WORKFLOW.md"]:::major-edit
        ClientEnv["ENVIRONMENT_SETUP.md"]:::major-edit
        ClientDebug["DEBUGGING.md"]:::major-edit
        ClientTest["TESTING.md"]:::major-edit
        ClientOnboard["ONBOARDING.md"]:::major-edit
        ClientPRTemplate[".github/pull_request_template.md"]:::major-edit
    end

    subgraph BankServer["bank-server Repository"]
        ServerREADME["README.md"]:::major-edit
        ServerCoding["CODING_STANDARDS.md"]:::major-edit
        ServerTrouble["TROUBLESHOOTING.md"]:::major-edit
        ServerContrib["CONTRIBUTING.md"]:::major-edit
        ServerWorkflow["DEVELOPMENT_WORKFLOW.md"]:::major-edit
        ServerEnv["ENVIRONMENT_SETUP.md"]:::major-edit
        ServerDebug["DEBUGGING.md"]:::major-edit
        ServerTest["TESTING.md"]:::major-edit
        ServerOnboard["ONBOARDING.md"]:::major-edit
        ServerPRTemplate[".github/pull_request_template.md"]:::major-edit
    end

    subgraph ExistingCode["Existing Codebase"]
        PackageJSON["package.json"]:::context
        ESLintConfig[".eslintrc.js"]:::context
        JestConfig["jest.config.js"]:::context
        EnvExample[".env.example"]:::context
    end

    ExistingCode --> BankClient
    ExistingCode --> BankServer

    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit
        L3["Context/No Edit"]:::context
    end

    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

Banking Domain Focus: All documentation emphasizes security-first development, financial precision using Decimal.js, double-entry bookkeeping principles, multi-currency support, and regulatory compliance requirements.

Coverage Requirements: Frontend maintains 98% test coverage threshold, backend requires 90% coverage with specific emphasis on transaction processing and security features.

Security Considerations: Documentation includes comprehensive security guidelines covering JWT authentication, input validation, audit logging, and banking-specific vulnerability prevention.

Link to Devin run: https://app.devin.ai/sessions/944d8aeae5c74aaab67f1ac1b92917ea
Requested by: @akkp-windsurf

[devin-ai-integration]

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