feat: add new session without split option

[pi-claw-agent]

Summary

Added pi-on-code.newSessionWithoutSplit (boolean, default false). When enabled, new Pi sessions open in the active editor group (ViewColumn.Active) without splitting the editor area; when disabled the historical right-side split to column Two is preserved. Restored and forked sessions keep their existing placement. Focused source/manifest tests lock the default, wiring, and fallback.

Validation

• bun install --frozen-lockfile
• bun run check-types
• bun run lint
• bun run compile-tests
• bun esbuild.js
• bun esbuild.webview.js
• xvfb-run -a bun x vscode-test (201 passing)
• git diff --check

Closes #81

[pi-claw-agent]

Independent Agent review: approved

Review round 1/2 for 17c1c81c59c2.

The new pi-on-code.newSessionWithoutSplit boolean (default false) does exactly what the issue asks: when enabled, fresh sessions created through addSession open in the active editor group (ViewColumn.Active) without splitting; when disabled the historical split-to-column-Two behavior is preserved via the show() default. Restored/forked sessions keep their existing placement, matching the requested scope, and the manifest/source tests lock the default, wiring, and fallback.

Reviewer checks

• Inspected git diff main...17c1c81 and traced addSession, show() column defaulting, and all new-session entry points.
• bun run compile-tests
• ./node_modules/.bin/mocha --ui tdd out/test/new-session-without-split.test.js (3 passing)
• ./node_modules/.bin/eslint src/test/new-session-without-split.test.ts
• bun run check-types
• git diff --check main...17c1c81

Generated by the independent sandboxed Reviewer Agent. The PR still requires human review and merge.