[FEATURE] Add Database Target and SSL Debug Logs for Scheduler Startup

### What's needed and why?

Add richer startup logging so operators can immediately see which database target the scheduler is using and why DB connection checks fail.

### Log parsed DB target details at scheduler startup

- In scheduler startup paths, parse DATABASE_URI and log:
-- type
-- database
--- host
-- user
- Do not log raw URI with password.

### Log SSL diagnostics

- Print whether SSL is enabled for the DB URI.
- Print whether a PEM/CA path is configured.
- If PEM path is configured, test readability by scheduler runtime context and log pass/fail.

### Improve connection error messages

- When DB connection retries/errors happen, include:
-- original exception message
-- masked DB target context (no password)
- Keep logs actionable for troubleshooting (“what failed” + “where we were connecting”).

### Implementations ideas (optional)

- Never print DB password in logs.
- Any URI shown must be masked or replaced by structured fields.

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct