Add oxlint import/no-cycle and break existing src/common cycles

Enable oxlint's import/no-cycle rule (import plugin) so circular module
dependencies are caught in CI, similar to eslint-plugin-import/no-cycle
and biome no-import-cycles discussed in the issue.

Relocate shared types and dependencies to remove cycles under src/common:

- Types.ts: host IInsertEvent, IDeleteEvent, IParams, UnderlineStyle,
  IBuffer, and IBufferSet; drop imports from CircularList, buffer/Types,
  parser/Types, and Services
- CoreTerminal.ts: define and export ICoreTerminal
- ServiceRegistry.ts: define IServiceIdentifier (break Services registry loop)
- UnicodeService: stop constructing UnicodeV6; CoreTerminal registers the
  default v6 provider after service creation
- buffer/Types.ts and parser/Types.ts: re-export moved types for callers

Fixes https://github.com/xtermjs/xterm.js/issues/5897

Co-authored-by: Cursor <cursoragent@cursor.com>

src/common/services/Services.ts

@@ -6,7 +6,7 @@
 import type { IDecoration, IDecorationOptions, ILinkHandler, ILogger, IWindowsPty, IOverviewRulerOptions } from '@xterm/xterm';
 import { CoreMouseEncoding, CoreMouseEventType, CursorInactiveStyle, CursorStyle, IAttributeData, ICharset, IColor, ICoreMouseEvent, ICoreMouseProtocol, IDecPrivateModes, IDisposable, IKittyKeyboardState, IModes, IOscLinkData, IWindowOptions } from '../Types';
 import { IBuffer, IBufferSet } from '../buffer/Types';
-import { createDecorator } from './ServiceRegistry';
+import { createDecorator, IServiceIdentifier } from './ServiceRegistry';
 import type { Emitter, IEvent } from '../Event';
 
 export const IBufferService = createDecorator<IBufferService>('BufferService');
@@ -119,12 +119,6 @@ export interface ICharsetService {
   setgCharset(g: number, charset: ICharset | undefined): void;
 }
 
-export interface IServiceIdentifier<T> {
-  (...args: any[]): void;
-  type: T;
-  _id: string;
-}
-
 export interface IBrandedService {
   serviceBrand: undefined;
 }