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/demographics.py

@@ -0,0 +1,41 @@
+from __future__ import annotations
+from pydantic import BaseModel, Field
+
+
+class AgeDistribution(BaseModel):
+    bracket: str
+    percentage: float
+
+
+class IncomeDistribution(BaseModel):
+    bracket: str
+    percentage: float
+
+
+class OccupationDistribution(BaseModel):
+    category: str
+    percentage: float
+
+
+class EthnicityDistribution(BaseModel):
+    group: str
+    percentage: float
+
+
+class DemographicProfile(BaseModel):
+    city_name: str
+    state: str
+    population: int
+    age: list[AgeDistribution] = Field(default_factory=list)
+    income: list[IncomeDistribution] = Field(default_factory=list)
+    occupations: list[OccupationDistribution] = Field(default_factory=list)
+    ethnicity: list[EthnicityDistribution] = Field(default_factory=list)
+    median_household_income: int = 0
+    poverty_rate: float = 0.0
+    unemployment_rate: float = 0.0
+    homeownership_rate: float = 0.0
+    median_rent: int = 0
+    rent_burden_rate: float = 0.0
+    college_education_rate: float = 0.0
+    median_age: float = 0.0
+    city_character: str = ""