Add directed split and pane control foundations for v0.7

[HelloThisWorld]

Summary

Prepare the draft winTerm 0.7.0-beta.1 Directed Split & Pane Controls work without resuming or modifying the Stable release flow.

This change adds explicit Top, Bottom, Left, and Right split commands relative to the focused pane; compact pane headers and a unified capability-aware pane menu; pane movement, docking-preview, transaction, history, and keyboard-move models; compiled coverage; documentation; and beta version metadata.

The PR intentionally remains Draft. Runtime pane-handle drag wiring, the live Snap overlay adapter, full regression coverage, and manual accessibility/session/DPI acceptance are still open and are documented in docs/v0.7-acceptance.md. No beta or stable tag has been created.

Related issues

None.

Detailed changes

• Add directed split planning for four explicit directions with focused-pane targeting, profile policy, size validation, and rollback-safe planning.
• Add compact pane-header presentation, accessible title/status text, overflow/context-menu entry points, and capability-aware command models.
• Reuse the existing docking model, layout transformer, preview, transaction, session ownership, and history foundations for pane movement.
• Add keyboard pane-move state and Narrator announcement models.
• Add TerminalApp split menus and runtime pane-header rendering while leaving unsupported live cross-process pane transfer disabled.
• Add Settings Model, TerminalApp, and Control tests plus source-boundary checks.
• Add user/developer documentation and an evidence-based v0.7 acceptance report.
• Set development metadata to 0.7.0-beta.1 / MSIX 0.7.0.1 while keeping the existing Stable workflow isolated on v1.0.2.
• Fix the package-output branding verifier and embed verifiable winTerm product metadata in WindowsTerminal.exe.

Validation performed

Environment: Windows x64, PowerShell 7.6.3, Visual Studio Community 2022 17.14.36, MSBuild x64, Windows SDK 10.0.22621/26100.

Passed:

• build.ps1 -Configuration Debug -Platform x64 -IncludeTests
• build.ps1 -Configuration Release -Platform x64 -IncludeTests
• Debug Relevant suite: 203 Settings Model, 51 TerminalApp, and 30 Control tests; zero failures/skips/blocked/not-run.
• Release Relevant suite: 203 Settings Model, 51 TerminalApp, and 30 Control tests; zero failures/skips/blocked/not-run.
• test.ps1 -Suite Smoke -Configuration Release -Platform x64 after rebasing onto the latest main.
• Release x64 MSIX generation and package-output version, identity, alias, executable metadata, signature, and checksum inspection.
• git diff --check.

Not yet passed or unavailable:

• The Full upstream suite stopped before execution because the current -IncludeTests path does not build Conhost.Unit.Tests.dll.
• Runtime docking UI automation adapter is not implemented.
• Manual live-session, Undo/Redo, workspace restore, mixed-DPI, Narrator, High Contrast, stress, and leak acceptance remains open.
• The local 0.7.0.1 package could not replace an already installed higher 1.0.2.0 package; temporary test-certificate trust was removed.

Checklist

• The change is focused and does not include unrelated formatting.
• Tests were added or updated where appropriate.
• All tests claimed above actually ran and passed.
• User-facing behavior and limitations are documented in this repository.
• Version or schema changes include compatibility and migration notes.
• Package identity, winterm.exe, and Microsoft Terminal coexistence remain isolated.
• No command text, terminal output, clipboard content, credentials, or private paths are logged.
• New source and script files contain the appropriate MIT license header.
• I did not include generated build output, secrets, certificates, or local absolute paths.