Add debug logging for payment session creation

[DeviPadmavathi-LE]

Summary

• Problem: Payment session lifecycle events (session start and creation) were not logged, making debugging and observability harder.
• Why it matters: When diagnosing issues in payment flows, it is useful to trace when a session request starts and when a session is successfully created.
• What changed: Added debug and info logging around payment session creation in payment_sessions.py.
• What did NOT change (scope boundary): No payment logic, API responses, session management behavior, or security logic were modified.

Change Type (select all that apply)

• Bug fix
• Feature
• Refactor
• Documentation
• Security hardening
• Tests
• Chore/infra

Scope (select all touched areas)

• Server / API endpoints
• Extensions (DID, x402, etc.)
• Storage backends
• Scheduler backends
• Observability / monitoring
• Authentication / authorization
• CLI / utilities
• Tests
• Documentation
• CI/CD / infra

Linked Issue/PR

• Closes #
• Related #

User-Visible / Behavior Changes

None. This change only adds internal logging and does not modify API responses or behavior.

Security Impact (required)

• New permissions/capabilities? (No)
• Secrets/credentials handling changed? (No)
• New/changed network calls? (No)
• Database schema/migration changes? (No)
• Authentication/authorization changes? (No)

Environment

• OS: Windows
• Python version: 3.12
• Storage backend: Default (memory)
• Scheduler backend: Default (memory)

Steps to Test

1. Start the server.
2. Call the POST /api/start-payment-session endpoint.
3. Check logs to confirm debug and info messages appear for payment session creation.

Expected Behavior

Payment session lifecycle events are logged, including session creation.

Actual Behavior

Logs show debug message when session request starts and info message when session is created.

Evidence (attach at least one)

• Failing test before + passing after
• Test output / logs
• Screenshot / recording
• Performance metrics (if relevant)

Human Verification (required)

• Verified scenarios: Payment session creation endpoint logging.
• Edge cases checked: None required as logic remains unchanged.
• What you did NOT verify: Full production payment flow.

Compatibility / Migration

• Backward compatible? (Yes)
• Config/env changes? (No)
• Database migration needed? (No)

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: Revert the logging lines in payment_sessions.py.
• Files/config to restore: bindu/server/endpoints/payment_sessions.py
• Known bad symptoms reviewers should watch for: None expected.

Risks and Mitigations

• Risk: Minimal increase in log output.
  • Mitigation: Logging is at debug/info level and does not affect logic.

Checklist

• Tests pass (uv run pytest)
• Pre-commit hooks pass (uv run pre-commit run --all-files)
• Documentation updated (if needed)
• Security impact assessed
• Human verification completed
• Backward compatibility considered