Add bb documents list and show

[codeforester]

Summary

Add read-only v2 document inspection commands so imported generic documents can be reviewed without opening SQLite manually.

Scope

• Add bb documents list to show imported BB_DOCUMENT rows in a compact table.
• Add bb documents show DOCUMENT_ID to show one document and its canonical object metadata.
• Keep SQL behind DAO/service helpers, not inline in CLI command bodies.
• Keep output parser-free and inference-free.
• Update README, changelog, and AI context.

Out of scope

• Filtering, sorting, pagination, JSON/CSV output.
• Document views under financial/views.
• Inbox processing.
• Parser detection or inferred observations.

Acceptance criteria

• uv run bb documents list shows imported generic documents.
• uv run bb documents show DOCUMENT_ID shows document metadata and canonical object metadata.
• Missing document IDs fail clearly.
• Existing bb documents import, bb status, and legacy commands continue working.
• Validation passes.

Follows #132.