feat(runtime): add first-class library API for framework libraries

[Flussen]

Motivation

• Provide a small, explicit framework-level API so official and third-party libraries can expose a consistent internal event bus and a namespaced external bridge while staying in runtime/* (not kernel).
• Keep the core runtime implementation tiny and tree-shakeable and ensure the client/runtime core never imports Node core modules (no events, fs, etc.).
• Align with existing logging and runtime layout patterns so libraries can get namespaced loggers and a minimal namespaced config accessor.

Description

• Added shared core types and primitives under src/runtime/core/library: types.ts, a tiny Map/Set createLibraryBus() (on/once/off/emit), createLibraryBase() and createLibraryConfigAccessor() with TSDoc explaining internal vs external events.
• Implemented createServerLibrary() in src/runtime/server/library that composes the base and exposes emitExternal(), emitNetExternal(), getLogger() and getConfig() and follows the exact naming convention opencore:<libName>:<eventName>.
• Implemented createClientLibrary() in src/runtime/client/library that composes the base and exposes emitServer(), getLogger() and getConfig() using the same namespaced convention.
• Exported the new APIs from runtime/core, runtime/server and runtime/client barrels and added lightweight tests/examples demonstrating internal bus behavior, buildEventName() and server/client wrapper usage.

Testing

• Ran pnpm -r build and the TypeScript build completed successfully.
• Ran pnpm -r test (unit + integration via Vitest) and the test suite passed: all tests executed successfully (including the new unit tests).
• Validated that the core/client runtime additions are pure TypeScript with no Node core-module imports and that the external event naming format is opencore:<libName>:<eventName> as enforced by buildEventName().

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Codex Task