internal/dependency: Manager.visited persists across top-level traversals, silently skipping dependencies #417

Problem

internal/dependency/manager.go keeps a single visited map (claim() / lines ~53-70 before the interface churn in #170) for the whole lifetime of a dependency.Manager. Every top-level traversal — AddAll, RefreshAll, and AddDependency's addPackage — consults it before recursing, but none of them resets it at entry.

A second top-level call on the same Manager therefore sees every ref as already claimed and returns immediately with no error and no sources: a dependency-schema generation silently becomes a no-op.

Impact

Today most commands build a Manager and run exactly one traversal, so the bug does not fire in the common one-command case. It bites:

• a retry of a traversal after a transient network/registry failure in the same process — the retry looks successful but generates nothing;
• any embedding or future refactor that runs two traversals on one Manager (the CollectSources-based merged-generation path landing in Project typescript support #170 has exactly this shape, and its resetVisited history comment documents the hazard);
• tests that reuse a manager fixture across cases.

Silent skip plus zero error output makes this a hard-to-diagnose failure mode when it does fire.

Suggested fix

Add a resetVisited() that reinitializes the map under the existing visitedMu, and call it at the start of each top-level traversal (AddAll/RefreshAll, AddDependency). ~15 lines plus a regression test asserting a second AddAll returns the same sources as the first instead of nothing.

Notes

A fix for this is already present on stevendborrelli:project-typescript-support (part of PR #170). Filing separately so it can land independently: cherry-pick the hunk onto main if desired, or close this on #170 merge if the fix-in-place in that PR is considered sufficient.