✨ Identity onboarding + Verbatim dialogue memory

- Added [identity] config section (agent_name, agent_role, user_name,
  user_role, setup_complete) to GyandootConfig and AgentConfig
- Agent loop now injects identity into system prompt on startup
- Agent loop injects past verbatim dialogue memory into system prompt
- Added dialogue_append() / dialogue_read() to MemPalace
  - Word-by-word, line-by-line verbatim record in dialogue.md
  - No compression, no truncation — every message preserved
- Agent loop writes to BOTH daily transcript AND verbatim dialogue
  on every turn
- All config paths pass identity through (flat converter, subagents)

src/main.rs

@@ -321,6 +321,7 @@ fn load_and_convert_config(path: &std::path::Path) -> Result<gyandoot_core::conf
             default: provider_name,
             providers: providers_map,
         },
+        identity: gyandoot_core::config::IdentitySection::default(),
         platform: gyandoot_core::config::PlatformSection::default(),
         memory: gyandoot_core::config::MemorySection::default(),
         gateway: gyandoot_core::config::GatewaySection::default(),