chore: initial commit

- Track MiroSociety source: backend (FastAPI), frontend (Vue3/Vite), docs, configs.
- Add start.sh / deploy.sh for local dev (uv venv + npm + dev servers on 31400/31401).
- Fix pyproject.toml: missing httpx dependency.
- Tighten .gitignore: .env, .venv, node_modules, data/, *.log, uv.lock, frontend/dist, etcd.

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/models/scenario.py

@@ -0,0 +1,17 @@
+from __future__ import annotations
+from pydantic import BaseModel, Field
+
+
+class SegmentDefinition(BaseModel):
+    name: str
+    description: str
+    count: int | None = None
+
+
+class ScenarioBrief(BaseModel):
+    world_description: str
+    rules_or_context: list[str] = Field(default_factory=list)
+    proposed_change: str | None = None
+    target_segments: list[SegmentDefinition] | None = None
+    population: int = 25
+    duration_days: int = 90