refactor: split util.js to reduce total and per-function complexity

[Copilot]

CodeQL flagged scanForFiles at cyclomatic complexity 24 and util.js total complexity at 75. Both stem from a single overloaded utility file and one deeply nested recursive function.

scanForFiles complexity (24 → ~3)

Extracted four module-level helpers so each unit of work is a flat, named function:

// Before: nested scan() + next() inside scanForFiles = complexity 24
function scanForFiles(directory, regexPattern, onEach, onDone) {
    function scan(dir, relativePrefix, isRoot, done) {
        fs.readdir(..., (err, entries) => {
            // classify, match, recurse — all inline
            function next() { ... }
            next();
        });
    }
    scan(directory, '', true, onDone);
}

// After: scanForFiles is a one-liner; logic lives in named helpers
function scanForFiles(directory, regexPattern, onEach, onDone) {
    scanDir(directory, '', true, regexPattern, onEach, onDone);
}
// visitMatchingPath / classifyEntries / scanSubdirs / scanDir — each ≤ complexity 4

Total util.js complexity

Relocated cohesive groups to more specific modules:

• src/fsUtil.js (new) — ensureDirectory, scanForFiles, and their extracted helpers. scanForFilesSync was removed as it had no remaining callers after the async storage open change.
• src/metadataUtil.js (existing) — buildMetadataHeader added here; it already owned the rest of the metadata serialization surface

All import sites across src/ updated accordingly; src/fsUtil.js added to package.json files.

[coveralls]

coverage: 97.964% (+0.3%) from 97.684% — copilot/address-codeql-feedback-utils into main

[albe]

@copilot address scanForFilesSync

[Copilot]

@copilot address scanForFilesSync

scanForFilesSync had no remaining callers after the async storage open change, so it's been removed entirely (db3eeb9).