Colocate buffer types in buffer/Types.ts

The import/no-cycle refactor had moved IBuffer, IBufferSet, and related
cell/line types into src/common/Types.ts, with buffer/Types.ts only
re-exporting them. That inverted the natural module boundary and made
buffer code depend on the top-level types hub.

Define buffer-owned types in buffer/Types.ts instead:
- CharData, IExtendedAttrs, IAttributeData, ICellData, IBufferLine
- IMarker, IBuffer, IBufferSet, BufferIndex

Restore UnderlineStyle to buffer/Constants.ts (used by IExtendedAttrs)
and remove those definitions from Types.ts.

buffer/Types.ts imports only what it needs from outside the buffer layer:
ICircularList and ICharset from Types, IDisposable from Lifecycle,
IEvent from Event, and UnderlineStyle from Constants. Types.ts does not
import buffer/Types.ts, so the previous Types <-> buffer cycle stays broken.

Update imports across common, browser, headless, addons, and tests to use
common/buffer/Types for buffer types rather than common/Types.

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

src/browser/services/CharacterJoinerService.test.ts

@@ -8,7 +8,7 @@ import { ICharacterJoinerService } from './Services';
 import { CharacterJoinerService } from './CharacterJoinerService';
 import { BufferLine } from '../../common/buffer/BufferLine';
 import { BufferLineStringCache } from '../../common/buffer/BufferLineStringCache';
-import { IBufferLine } from '../../common/Types';
+import { IBufferLine } from '../../common/buffer/Types';
 import { CellData } from '../../common/buffer/CellData';
 import { MockBufferService, createCellData } from '../../common/TestUtils.test';
 

src/browser/services/CharacterJoinerService.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { IBufferLine, ICellData, CharData } from '../../common/Types';
+import { CharData, IBufferLine, ICellData } from '../../common/buffer/Types';
 import { ICharacterJoiner } from '../Types';
 import { AttributeData } from '../../common/buffer/AttributeData';
 import { WHITESPACE_CELL_CHAR, Content } from '../../common/buffer/Constants';

src/browser/services/SelectionService.test.ts

@@ -6,14 +6,13 @@
 import { assert } from 'chai';
 import { SelectionService, SelectionMode } from './SelectionService';
 import { SelectionModel } from '../selection/SelectionModel';
-import { IBufferLine } from '../../common/Types';
+import { IBuffer, IBufferLine } from '../../common/buffer/Types';
 import { MockBufferService, MockOptionsService, MockCoreService, MockMouseStateService, createCellData } from '../../common/TestUtils.test';
 import { BufferLine } from '../../common/buffer/BufferLine';
 import { BufferLineStringCache } from '../../common/buffer/BufferLineStringCache';
 import { IBufferService, IOptionsService } from '../../common/services/Services';
 import { MockCoreBrowserService, MockMouseService, MockRenderService } from '../TestUtils.test';
 import { CellData } from '../../common/buffer/CellData';
-import { IBuffer } from '../../common/buffer/Types';
 import { IRenderService } from './Services';
 
 const TEST_STRING_CACHE = new BufferLineStringCache();

src/browser/services/SelectionService.ts

@@ -11,10 +11,10 @@ import { ISelectionRedrawRequestEvent, ISelectionRequestScrollLinesEvent } from
 import { ICoreBrowserService, IMouseCoordsService, IRenderService, ISelectionService } from './Services';
 import { Disposable, MutableDisposable, toDisposable } from '../../common/Lifecycle';
 import * as Browser from '../../common/Platform';
-import { IBufferLine, ICellData, IDisposable } from '../../common/Types';
+import { IDisposable } from '../../common/Types';
+import { IBuffer, IBufferLine, ICellData } from '../../common/buffer/Types';
 import { getRangeLength } from '../../common/buffer/BufferRange';
 import { CellData } from '../../common/buffer/CellData';
-import { IBuffer } from '../../common/buffer/Types';
 import { IBufferService, ICoreService, IMouseStateService, IOptionsService } from '../../common/services/Services';
 import { Emitter } from '../../common/Event';