Update Flyde imports when referenced files move

[shiv-999]

Fixes #112.

Fixes broken local .flyde imports after a referenced visual node file is moved in VS Code.

When VS Code reports a .flyde file rename/move, the extension now scans workspace .flyde files and rewrites any matching local relative import path to point at the file's new location. Package imports are left unchanged.

Validation:

• Added a focused test for updating a moved local visual node import and preserving unrelated imports.
• Ran git diff --check successfully.

Note: I could not run the full TypeScript test suite locally because this shell does not have Node.js/pnpm available.

[shiv-999]

Closing after local validation found that the focused regression test fails: the implementation reads deprecated top-level imports after loader migrations have removed them, and it does not cover the current source: file representation or moves of the importing flow. Existing submissions already cover the broader rename cases, so this PR should not remain open as a duplicate.