test: rewrite the test suite, test plans and CI

[datlechin]

Why

• A PR waited 2 to 3 hours for a verdict: 7 macOS jobs, 173 runner minutes per run, on a 5-job cap.
• 88% of red runs inherited a broken main from a PR merged before its gate finished.
• The suite carried tests for registry-only engines, source-reading guards and duplicates.

Change

• One macOS Tests job builds once, runs the Unit plan, then the UI plan. iOS and Package Tests adds the TableProCore and Oracle packages.
• Tests for the 25 registry-only drivers, duplicates and trivia are gone. Source-reading guards are now SwiftLint rules and scripts/ci checks.
• The UI suite is 47 flows on a 6-table fixture, down from 297 cases. Unit and UI runs never touch the real defaults or Application Support.
• verify.sh reads its verdict from the result bundle. A filter that runs nothing fails.

Verified

• Unit plan: 25,073 executed, 0 failures, 260 s. The UI flows run for the first time on this PR.

Not in this PR

• Draft. Plugin and app-area tests move into packages in later commits on this branch.
• The ruleset still requires the old gate checks. It changes at merge.
• The next release needs the release deploy key first.