Optimize managed history trimming

[corasan]

Summary

• replace linear managed-history trimming tokenization with a binary-search planner
• add a Swift spy/counter test for trim planning probe counts and boundary cases
• add a manual trim debug path in the example app with clearer progress UI and a scrollable header action rail

Tests

• bun run test
• bun tsc -p ./package --noEmit
• bun run test:ios-history-trim
• xcrun swiftc -parse package/ios/Sources/ManagedHistoryTrimPlanner.swift package/ios/Sources/HybridLLM.swift

Note

• example-wide typecheck still fails on existing Node globals in example/metro.config.ts (__dirname/module) because the example tsconfig does not include Node types.