feat(verisimdb): implement Groove Protocol connect/disconnect lifecycle

Add groove.rs module to verisim-api with connect/disconnect/heartbeat/
status endpoints at /.well-known/groove/*. Uses in-memory HashMap for
connection tracking with heartbeat timeout detection on status checks.
Capability manifest declares octad-storage, drift-detection, provenance,
vector-search, spatial-search, and VQL capabilities. Includes unit tests
for manifest, session ID generation, and capability matching.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath