bug(web): Intermediate directory nodes in buildFileTree receive child leaf paths instead of directory paths #1707

Describe the Bug

In packages/web/src/features/git/utils.ts, buildFileTree constructs a nested FileTreeNode hierarchy from a flat list of { type, path } objects.

When creating intermediate directory nodes (lines 68-74), the new node's path property is assigned item.path (the full path of the current leaf file being processed), instead of the path of that directory:

// packages/web/src/features/git/utils.ts:67-75
if (!next) {
    next = {
        name: part,
        path: item.path, // <--- Bug: assigns leaf file's path to intermediate directory node
        type: nodeType,
        children: [],
    };
    current.children.push(next);
}

Impact

1. Broken Folder State & Expansion in UI: In packages/web/src/app/(app)/browse/components/fileTreePanel.tsx, folder expand/collapse state is tracked via openPaths.has(node.path) and route sync via pathParts.slice(0, i + 1).join('/'). Because directory nodes receive the child file's path instead of their own directory path, clicking folders or deep-linking to nested paths causes folder state tracking and auto-expansion to fail.
2. Public API Corruption: The getTree endpoint (/api/git/tree) returns FileTreeNode with corrupted directory paths to API consumers.

Reproduction

const flatList = [
    { type: 'blob', path: 'src/components/buttons/PrimaryButton.tsx' }
];

const tree = buildFileTree(flatList);
const srcDir = tree.children[0];
console.log(srcDir.name); // "src"
console.log(srcDir.path); // Expected "src", but Got "src/components/buttons/PrimaryButton.tsx"

Proposed Fix

Reconstruct the directory node's path using parts.slice(0, i + 1).join('/'):

if (!next) {
    next = {
        name: part,
        path: parts.slice(0, i + 1).join('/'),
        type: nodeType,
        children: [],
    };
    current.children.push(next);
}

For intermediate directory levels (i < parts.length - 1), this evaluates to the proper directory path (e.g. "src", "src/components"), and for leaf files (i === parts.length - 1), it matches item.path.