Template Server Identity Owns Runtime Key Semantics

Template identity was previously encoded in multiple string formats across pooling, routing, adapter lookup, and cleanup. We decided to introduce Template Server Identity in src/core/server/templateIdentity.ts as the canonical owner for typed identity forms, rendered-hash creation from already-rendered configs, key serialization, and lookup candidate order, while keeping ConnectionResolver as the OutboundConnections lookup facade. This preserves session-first routing and avoids spreading storage-map key semantics across runtime callers.