fix: add verified MSIX CDP launch fallback

[joonas-001]

Closes #25.

What changed

• Keep IApplicationActivationManager as the first-choice Store/MSIX launch path.
• When AUMID activation starts Codex without preserving the CDP arguments, stop that exact owned instance and retry once through the executable declared by the same verified MSIX package and AUMID.
• Validate the immutable resolver tuple, exact package full name, install root, AUMID application entry, executable basename, path containment, and file existence before the fallback launch.
• Add injectable launch/process providers and regression coverage for sequencing and path-traversal rejection.
• Update the terminal diagnostic so a failure after both launch paths is explicit.

Why

Codex Store/MSIX 26.727.6591.0 can accept an AUMID activation request while dropping --remote-debugging-* from the resulting ChatGPT.exe command line. HeiGe then waits twice and exits before CDP or injection state is initialized.

The fallback does not modify WindowsApps, app.asar, application signatures, or binaries. It launches only the executable declared by the exact installed Store package already bound by HeiGe's immutable app identity.

Validation

• Windows PowerShell 5.1 parser: both changed PowerShell files parse without errors.
• New regression tests pass:
  • exact bound MSIX executable resolution and traversal rejection;
  • one AUMID attempt followed by one verified package-executable attempt with exact CDP arguments.
• git diff --check: pass.
• Windows launcher/security contract tests: 2 pass; one unrelated Node CLI contract test is blocked by the current sandbox's non-private temporary-directory ACL.
• Full entrypoints.test.ps1: both new tests pass; four pre-existing filesystem/process tests are blocked by the current sandbox denying their LOCALAPPDATA test paths.
• Read-only live evidence: the current Store process is OpenAI.Codex_26.803.5235.0_x64__2p2nqsd0c76g0\app\ChatGPT.exe; the file exists and has a valid OpenAI OpCo, LLC Authenticode signature.

Verification boundary

No live patched apply was run because it would close/restart the Codex instance hosting this task and the current sandbox cannot safely write the required AppData state. The PR therefore does not claim a completed Store/MSIX end-to-end injection; Windows CI and a maintainer/user Store acceptance run are still required.