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/CircularList.ts

@@ -3,19 +3,11 @@
  * @license MIT
  */
 
-import { ICircularList } from './Types';
+import { ICircularList, IDeleteEvent, IInsertEvent } from './Types';
 import { Disposable } from './Lifecycle';
 import { Emitter } from './Event';
 
-export interface IInsertEvent {
-  index: number;
-  amount: number;
-}
-
-export interface IDeleteEvent {
-  index: number;
-  amount: number;
-}
+export type { IDeleteEvent, IInsertEvent } from './Types';
 
 /**
  * Represents a circular list; a list with a maximum size that wraps around when push is called,