Workflow dispatch fails for workflows in git submodules

使用一個在 .github/workflows/deploy.yml 中包含 submodule workflow 的父儲存庫，透過 Trigger Run 或 GitHub Actions explorer 重現此故障。追蹤 workflow-dispatch 路徑，以及如何識別已開啟檔案所屬的儲存庫。完成標準是 dispatch 以 submodule 儲存庫為目標，且不再發生 404。

Describe the bug
When attempting to trigger a GitHub Actions workflow located in a git submodule (e.g., host/.github/workflows/deploy.yml), the extension fails with a 404 "Not Found" error. The extension incorrectly attempts to dispatch the workflow to the parent repository instead of the submodule's separate GitHub repository.

To Reproduce
Steps to reproduce the behavior:

1. Have a git repository with a submodule that has its own separate GitHub repository
2. The submodule contains GitHub Actions workflows in .github/workflows/
3. Open the workflow file in VSCode
4. Right-click and select "Trigger Run" or use the GitHub Actions explorer
5. See error: 404 Not Found or similar repository not found error

Expected behavior
The extension should:

1. Detect that the workflow is located in a git submodule
2. Identify the correct GitHub repository for that submodule
3. Dispatch the workflow to the correct repository, not the parent

Screenshots
The error appears in the VSCode debug console when attempting to dispatch a workflow in the web submodule:

The extension is attempting to dispatch to the parent repository instead of the submodule's separate GitHub repository.

A user-facing error notification is displayed:

Note: Request IDs and repository names in the screenshot have been redacted for privacy.

Extension Version
v0.31.5

Additional context
This occurs in monorepo setups where submodules are separate GitHub repositories with their own workflows.

monorepo/                              (Parent repo: github.com/owner/monorepo)
└── submodule/                         (Submodule: github.com/owner/submodule)
    └── .github/workflows/
        └── deploy.yml                 ← Should dispatch to submodule repo

The extension's workflow dispatch logic needs to be aware of git submodules and route dispatch requests to the appropriate repository.