Add bb init and v2 storage readiness checks

[codeforester]

Summary

Add the first self-sufficient bb lifecycle command so the v2 CLI can initialize and inspect the financial-intelligence foundation without relying on the legacy bankbuddy command surface.

Scope

• Add bb init to initialize the active data home with current migrations.
• Ensure v2 financial storage directories are created during initialization.
• Keep existing bankbuddy init and taxbuddy behavior unchanged.
• Improve bb status readiness output if needed so v2 schema and storage readiness are clear.
• Add tests for init, idempotency, and status output.

Out of scope

• Generic document import.
• Parser migration.
• Removing legacy commands or tables.

Acceptance criteria

• uv run bb init initializes the active data home.
• uv run bb status reports initialized v2 foundation and storage readiness.
• Running bb init twice is safe.
• Existing bankbuddy and taxbuddy entrypoints remain configured.
• Validation passes.