fix(sync): filter git-status fast path through ignore matcher

[itxaiohanglover]

What

Fixes #766

The incremental sync's git fast path consumed git status --porcelain output without filtering through buildDefaultIgnore, so tracked files in default-ignored dirs (node_modules/, vendor/, etc.) leaked back into the index on every sync — disagreeing with a full index --force.

The fix

Build the shared buildDefaultIgnore(this.rootDir) matcher once and continue past ignored paths in the modified+added loop. Deleted files stay unfiltered — removal is always correct for stale entries, and it lets a newly-excluded dir's old entries clean up.

Same approach suggested by @monochrome3694 in the issue, verified locally on a ~1,100-file workspace.

Testing

• Added regression test: commits a .ts file inside node_modules/, modifies it, and verifies sync() does not index it (filesAdded: 0, filesModified: 0).
• All 15 existing + new sync tests pass.
• tsc --noEmit clean.

[psandeep02]

The added code appears to:
Create an ignore matcher:
TypeScript
const ig = buildDefaultIgnore(this.rootDir);
Loop through modified and added Git files:
TypeScript
for (const filePath of [...gitChanges.modified, ...gitChanges.added]) {
Skip files that match .gitignore or default ignore patterns:
TypeScript
if (ig.ignores(filePath)) continue;
Why this is useful
The comments explain the intent clearly:
Prevent tracked files inside ignored directories (such as vendor/) from being indexed.
Ensure behavior matches the same ignore rules used elsewhere (getGitVisibleFiles).
Avoid indexing files that Git reports as changed but should be ignored.
Positive points
✅ Good explanatory comments.
✅ Reuses existing ignore logic instead of creating new rules.
✅ Helps maintain consistency between file discovery and indexing.
✅ Likely fixes the issue mentioned (#766) by preventing ignored files from leaking into the index.
Things to verify
⚠️ Ensure buildDefaultIgnore(this.rootDir) is not recreated repeatedly in a hot path if this function runs frequently.
⚠️ Confirm that intentionally tracked files inside ignored directories should indeed be skipped. Some repositories commit files under directories that are normally ignored.
⚠️ Add or verify unit tests for:
Files ignored by .gitignore
Tracked files inside ignored folders
Modified files not ignored
Added files not ignored
Overall Review
Rating: 8.5/10
The change is clean, readable, and appears to solve a real edge case while keeping behavior consistent with Git visibility rules. The comments are especially helpful for future maintainers.