Fix zellij team pane cleanup and terminal labels

[takemo101]

Summary

• persist and restore zellij team pane labels so terminal renames keep <position>:<task_id> [status] after process restart
• rename panes on terminal transitions/cancel and add zellij team-session teardown hooks
• wire cleanup_team through CLI/MCP/TUI contexts so the shared zellij session is killed when the last team task is removed

Validation

• bun run --filter @cuekit/mcp typecheck
• bun run --filter @cuekit/adapters typecheck
• bun test packages/mcp/tests/commands.test.ts packages/mcp/tests/tui-context.test.ts
• CUEKIT_ZELLIJ_INTEG=1 bun test packages/adapters/tests/zellij-backend-integ.test.ts
• bun run bundle
• git diff --check

Closes #419
Closes #420