feat: make human avatars identifiable and traceable

[SignalLayerLabs]

Make HUMAN_LINKED Citizens identifiable, traceable, and useful to their owners without changing CYMONIA's canonical autonomy.

• Automatically ensure the authenticated GitHub user's avatar on page load
• Keep avatar creation idempotent and avoid unnecessary persistence writes
• Return session-backed avatar ownership data to the Observer
• Distinguish LIVING / TOTAL / HUMAN / VISIBLE population counts
• Add a permanent YOU marker for the owned Citizen
• Add a distinct owned-Citizen minimap marker
• Add Locate / Follow / Inspect controls
• Turn My Avatar into a personal evolution dashboard
• Show health, knowledge count, vocabulary, relationships, possessions, current action, goal and recent life events
• Preserve HUMAN_LINKED privacy in public world state
• Keep avatar death permanent and subject to normal world rules

Verification:

• 4/4 avatar ownership tests passed
• 108/108 Sovereign tests passed
• deterministic Genesis replay passed
• package manifest passed
• full browser smoke passed