feat(api): add terminal WebSocket gateway with PTY session management

Implements CT-TERM-001: WebSocket-based terminal service that spawns real
shell sessions via node-pty and streams I/O to connected clients.

- Add node-pty dependency and configure pnpm build permissions
- Create TerminalModule with Gateway, Service, and DTOs
- TerminalGateway: /terminal namespace, auth via handshake token,
  workspace-scoped rooms, handles terminal:create/input/resize/close events
- TerminalService: manages IPty sessions per workspace with max 10 session
  limit, cleanup on disconnect
- DTOs: CreateTerminalDto, TerminalInputDto, TerminalResizeDto, CloseTerminalDto
  with class-validator decorators
- Unit tests: 25 gateway tests + 23 service tests (all passing)
- Register TerminalModule in AppModule

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pnpm-workspace.yaml

@@ -3,13 +3,14 @@ packages:
   - packages/*
 
 ignoredBuiltDependencies:
-  - '@nestjs/core'
-  - '@swc/core'
+  - "@nestjs/core"
+  - "@swc/core"
   - better-sqlite3
   - esbuild
   - sharp
 
 onlyBuiltDependencies:
-  - '@prisma/client'
-  - '@prisma/engines'
+  - "@prisma/client"
+  - "@prisma/engines"
   - prisma
+  - node-pty