Get Lifecycle Stage Counts

Per-stage company counts — cheap enough to power a lifecycle board header.

The returned map is keyed by lifecycle ENTRY ID, not slug (matches GET /settings/revenue/lifecycle/counts exactly — see .claude/agent-context/lifecycle-stage-moves.md Gotcha 4). Cross-reference against GET /lifecycle-stages to resolve an id to its slug/name. Counts are company-only, same as the app's nav badges — contact-stage membership has no counts surface yet (see the module docstring's dropped-scope note).