Configure Karma to properly serve the decisions_core_bg.wasm file during
UMD bundle browser tests, resolving the "Cannot read properties of undefined
(reading 'wasmdecisionengine_new')" error.

Changes:
- Added WASM file to Karma files array with {included: false, served: true}
- This allows the UMD bundle to fetch the WASM file via HTTP during tests
- WASM file is already copied to lib/ by copy-wasm.js during build

The pkg-node/browser/ version of decisions-core uses async WASM loading
which requires the WASM file to be accessible via fetch(). By serving it
through Karma, the browser tests can now properly initialize the Rust
decision engine.

Note: CJS browser tests at index.browser.cjs.tests.js cannot use Rust
decider because pkg-node/decisions_core.js uses require('fs') which is
not available in browsers. These tests should either be skipped when
useRustDecider is enabled, or they should test fallback behavior only.

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Co-Authored-By: Claude <noreply@anthropic.com>

- Renamed all 'Rust' references to 'Core' in variable names, class names, methods, and config properties
- Renamed rust-decider.ts to core-decider.ts
- Updated config property from useRustDecider to useCoreDecider
- Added CoreDecider type definition in types package
- Updated DataManagerInterface to properly expose coreDecider property
- Fixed Rollup configuration to use browser version of decisions-core for UMD bundles
  - Added exportConditions for proper conditional exports resolution
  - Ensures __dirname is not present in browser bundles

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Updated test hooks to properly await SDK initialization when using
Core decider. The WASM module loads asynchronously, so tests must
wait for the READY event before calling createContext().

Changes:
- Made test "Shoud successfully create visitor context" async and added await
- Updated "Basic SDK methods" before() hook to be async and await onReady()
- Updated "Test invalid visitor" before() hook to be async and await onReady()

All 20 UMD browser tests now pass with Core decider enabled.

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Co-Authored-By: Claude <noreply@anthropic.com>

- Standardized import statement formatting with spaces around braces
- Updated error log message from "Rust decider" to "Core decider"
- Updated yarn.lock after dependency reinstallation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

- Reordered demo instructions: build packages before starting servers
- Added build step to Installation section
- Fixed typo: "Prevview" → "Preview"
- Fixed typo: "enviroment" → "environment"

All demos now follow: Build → Create env → Start → Test

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Co-Authored-By: Claude <noreply@anthropic.com>