add minimal JSON schema

[cjyetman]

Adds a JSON schema to validate frontend/src/data/scenarios_metadata.json

• adds schema frontend/pbtar_schame.json
• adds acv-cli to frontend/package.json
• updates frontend/package-lock.json appropriately with the addition of acv-cli
• adds a json:check "script" to frontend/package.json to run the JSON validator
• adds a GitHub action to run the JSON validator whenever frontend/pbtar_schame.json, frontend/src/data/scenarios_metadata.json, or .github/workflows/frontend-json.yml is changed

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/pbtar_api/models
pydantic_models.py	59	59	0%	1–101
src/pbtar_api/routers
endpoints.py	45	25	44%	15, 20–21, 30–33, 40–43, 50–53, 60–63, 72–86
src/pbtar_api/services
auth.py	12	3	75%	16–18
db.py	14	4	71%	18–22
TOTAL	208	91	56%

Tests	Skipped	Failures	Errors	Time
6	0 💤	0 ❌	0 🔥	2.822s ⏱️

[jdhoffa]

Testing locally now

minimal require and additionalProperties settings have been added

[jdhoffa]

looks good