test(web): 为 bootstrapSession 增加显式测试 reset hook

[ghbvf]

Source

From PR #65 review follow-up: #65 (comment)

Context

Cx3 legacy item: bootstrapSession currently has no _resetBootstrapForTesting hook. Tests rely on vi.resetModules(), which works today, so PR #65 intentionally did not add a YAGNI export.

Desired direction

Add an explicit test-only reset hook only if bootstrap tests become brittle, slow, or need to coordinate multiple bootstrap cycles in one module instance. Keep it out of production app assembly semantics.

Acceptance

• Bootstrap tests can reset bootstrap singleton state without relying on module cache resets.
• The hook is clearly test-only and does not become part of public runtime API.
• Existing cold-start refresh behavior remains covered.