[bai-agent] Ship a webui-map snapshot in the CLI package with staleness degradation

## Parent

FR-3740 — step G. Lets a `bai-agent` without a checkout still answer "where is X".

## What to build

- Add `data/webui-map.json` (+ ids snapshot) to the package `files[]` at build time, stamped with `repoVersion` and `generatedAt`.
- Resolution order: checkout map (if `data/webui-map.json` exists) → shipped snapshot. `doctor` warns when the snapshot is older than `SCHEMA_META_STALE_DAYS` (reuse the schema.meta mechanism) or its `repoVersion` is behind the connected manager's WebUI version.
- When answering from a stale snapshot, `where`/`explain` **degrade**: assert the page path only, never the tab/setting id, and say so in the output (`source: snapshot (stale)`).

## Acceptance criteria

- [ ] `npm pack` output contains the snapshot; `where` works in an empty directory.
- [ ] Stale snapshot → tab-level answers are withheld with an explicit note; fresh checkout map wins when present.

## Blocked by

- Steps C, D.

JIRA Issue: FR-3779

Start with the CLI package's packaging configuration and the data/webui-map.json snapshot, then trace the doctor, where, and explain commands and the existing schema.meta staleness mechanism. Use npm pack to verify the snapshot is included and test resolution in an empty directory; done means checkout maps take precedence, stale snapshots withhold tab-level answers and report their source, and fresh snapshots resolve normally.

Written by the indexing model from the issue text.