Add scenario SQL smoke runner

[bill-ph]

Summary

• add tests/scenario/sql for PGWire SQL and inline SQL catalog scenario steps
• add SNI/hostaddr DSN generation, transient startup retry handling, and SQL result recording
• wire scripts/scenario_run.sh, just scenario-smoke, just scenario, and just test-scenario
• replace the fake provision smoke with provision -> wait -> SELECT 1 -> deprovision
• add a scenario runner runbook with dev cleanup guidance

Tests

• go test -count=1 ./tests/scenario/...
• just test-scenario
• just lint

Review

• Ran one review pass and fixed the findings around Go test timeout, run-unique smoke org/database names, shipped YAML validation, and docs for connect timeout.

[github-actions]

Test Impact Plan

Deterministic summary of how this PR changes tests, CI runners, and coverage-risk signals.

Summary

Area	Added	Changed	Deleted
Test files	8	1	0
E2E/journey files	0	0	0
Workflow files	0	0	0

Signals

• Test cases: +12 / -0
• Assertions: +48 / -0
• Skips or known failures added: 1
• Workflow continue-on-error added: 0
• Workflow path filters added: 0
• Test commands removed from justfile: 0
• E2E/journey retry lines added: 0

Coverage risk: likely reduced

Warnings

• New skips or known failures (likely reduced)
  • 1 skip/allowlist line(s) added