Compact and harden devtools statecharts

[SandroMaglione]

Summary

• compact state cards and switch the default topology to a denser top-to-bottom flow
• move state value types into a concise JSON-shaped inspector preview and preserve machine-tab scroll position
• harden route attachment, initial markers, self-loops, labels, and hierarchy crossings
• render the best deterministic layout when its only remaining issues are cosmetic label-to-route crossings
• add a 13-state shared-terminal routing example and regression coverage for issue Devtools rejects usable chart when transition labels overlap routes #188

Fixes #188

Changeset

• Added or updated for a library or package-metadata change
• Not required because this PR does not change a publishable package

Validation

• pnpm check
• Automated type-performance measurement passed or was not required
• Automated runtime- and memory-performance measurement passed or was not required

Local runtime and memory performance smoke test completed successfully. The pull-request workflows provide the authoritative base comparison.