feat: migrate adapters to sdk

[michaelmalave]

Summary

This PR continues SDK integration cleanup on top of feat/heroku-sdk-integration by simplifying PG, addons, and pipelines command internals while preserving behavior. Scope is focused on removing obsolete PG adapter indirection, tightening direct SDK call paths, and updating affected tests/mocks.

• Remove src/lib/pg/sdk-adapter.ts and migrate remaining PG command usage to direct SDK calls
• Refactor PG backups, credentials, and upgrade commands to align with the direct-call SDK pattern
• Refactor addons/pipelines command flows and related disambiguation/log-display logic for SDK consistency
• Update shared SDK mocks and unit tests across addons, PG, and pipelines command suites to match new call patterns

Type of Change

• fix: Bug fix or issue (patch semvar update)
• feat: Introduces a new feature to the codebase (minor semvar update)
• perf: Performance improvement
• docs: Documentation only changes
• tests: Adding missing tests or correcting existing tests
• chore: Code cleanup tasks, dependency updates, or other changes

Verification

Build and Testing Pass

npm install && npm run build
npm run test

Additional Context

• Breaking: none expected
• Risk: low to medium; internal command-path refactors with broad test updates
• Merge target: feat/heroku-sdk-integration

Related Issue

GUS work item: W-22782530

[tlowrimore-heroku]

LGTM!