fix(vscode): update Flyde imports after file moves

[ldthang0612]

/claim #112

Summary

• updates local .flyde import paths when VS Code reports .flyde file rename/move events
• handles both moving the imported flow and moving the importing flow
• keeps the updater logic covered by focused unit tests

Verification

• corepack pnpm --filter flyde-vscode compile-tests
• corepack pnpm --filter flyde-vscode lint (passes with existing warnings in unrelated files)
• node node_modules\.pnpm\mocha@10.8.2\node_modules\mocha\bin\mocha.js --ui tdd vscode\out\test\updateMovedFlydeImports.test.js

Notes

• AI-assisted with Codex; I reviewed the diff and ran the verification above.
• I attempted the full VS Code integration runner, but it timed out locally after about 184s without a specific failure output.

[ldthang0612]

Added a short visual demo of the moved-import behavior here:

The flow shown in the demo is the covered regression path:

• before: Parent.flyde imports ./nested/Child.flyde
• move: nested/Child.flyde -> shared/Child.flyde
• after: the extension updates the import to ./shared/Child.flyde

This is covered by vscode/src/test/updateMovedFlydeImports.test.ts.