test+feat: add cargo workspace crate resolution for rust resolver (#151)

* test+feat: add cargo workspace crate resolution for rust resolver

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Co-authored-by: miketheman <529516+miketheman@users.noreply.github.com>

* perf: cache cargo workspace map during rust resolution

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* feat(rust): expand cargo workspace member globs and trust workspace hits

- Parse glob entries in `[workspace].members` (e.g. `crates/*`,
  `helix-*`) via picomatch against a new optional
  `ResolutionContext.listDirectories` so workspaces that don't
  enumerate every member are covered. Implementation walks the
  static-prefix subtree with a depth cap and skips `target`,
  `node_modules`, `.git`, etc.
- Bump Pattern 4's confidence to 0.95 when the workspace map
  produces a hit. The cargo manifest gives an unambiguous
  crate-name -> crate-root mapping, so workspace-driven module
  resolution should beat name-matcher's self-file matches
  (otherwise every file with `use foo::...` self-resolves at 0.7
  and the cross-crate edge never materializes).
- Validated against astral-sh/uv (`members = ["crates/*"]`,
  67 crates, 567 .rs files): 1,969 cross-crate `imports` edges
  reaching 60 distinct member lib.rs files, up from 0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Colby McHenry <me@colbymchenry.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/resolution/index.ts

@@ -257,6 +257,24 @@ export class ReferenceResolver {
         return this.queries.getAllFilePaths();
       },
 
+      listDirectories: (relativePath: string) => {
+        const target = relativePath === '.' || relativePath === ''
+          ? this.projectRoot
+          : path.join(this.projectRoot, relativePath);
+        try {
+          return fs
+            .readdirSync(target, { withFileTypes: true })
+            .filter((entry) => entry.isDirectory())
+            .map((entry) => entry.name);
+        } catch (error) {
+          logDebug('Failed to list directory for resolution', {
+            relativePath,
+            error: String(error),
+          });
+          return [];
+        }
+      },
+
       getNodesByLowerName: (lowerName: string) => {
         const cached = this.lowerNameCache.get(lowerName);
         if (cached !== undefined) return cached;