feat: add focused NPC dialogue portrait

[JOY (JOY)]

Summary

• add a focused NPC portrait column with stable initials fallback, role, status, and compact source state
• align NPC messages on the NPC side and player messages on the opposite side in focused dialogue
• add text-timed NPC response reveal that starts and stops a presentation-only speaking state, including cleanup on complete, failure, and dialogue exit
• keep dialogue focus as neutral/non-combat stance instead of continuously driving the NPC speaking animation while listening

Verification

• git diff --check
• local code-review fallback: checked Unity/Nakama/LLM authority boundaries and changed files only touch presentation/UI state
• attempted Unity 6000.5.0b9 batchmode compile for Unity/, but Package Manager stopped before script compilation with the known worktree blocker: Failed to resolve packages: The "path" argument must be of type string. Received undefined. No packages loaded. Log: Unity/Logs/dialogue-portrait-batchmode.log
• Unity MCP custom tools/instances checked; no active Unity Editor session was available, so Play Mode smoke could not run in this turn

Issue

Refs #139