[anton-gor-dev]

Summary

• State History in the inspector State panel rendered the full state snapshot for every entry, which became an unreadable wall of JSON for composables with large or frequently-changing state, and gave no indication of what actually changed between two adjacent entries.
• Added diffSnapshotValues, which recursively compares a snapshot against the previous (older) one and returns a flat map of path: "from → to" strings for every leaf value that changed (e.g. user.profile.name: "a → b"). Nested objects are drilled into so only the actually-changed leaf is reported — not the whole containing object — keeping diffs readable even for deeply nested state. Arrays are compared and reported as whole values rather than recursed into by index.
• Each history entry's value is now this flat diff map directly — one level of nesting (entry → changed field), matching how State itself is displayed, with no extra wrapper objects to expand.

Closes #25

Test plan

• pnpm vitest run packages/plugin passes (added unit tests for diffSnapshotValues, including nested-object and array cases)
• pnpm lint passes