Add homelab dashboards: system, LLM, and UPS on one domain

Three dashboards served by one FastAPI app with a SQLite history store
(raw / 1m / 1h) and hand-written SVG charts: no Prometheus, no Grafana,
no CDN, no build step. Nothing is fetched from the internet at runtime.

* system: a stdlib-only agent (agent/host_agent.py) reports /proc and
  /sys counters; the dashboard turns them into rates over a labelled
  window, so every number says how it was measured.
* llm: gufo/llama.cpp and vLLM /metrics are parsed by an in-house
  exposition parser. Measured delta/elapsed throughput beats a native
  per-request gauge, and each value carries its provenance.
* ups: a NUT wire-protocol client plus health checks that name what
  they looked at. Commands are gated by NUT_ALLOW_ACTIONS,
  DASH_READ_ONLY and a DANGER confirmation, re-checked server-side.

Missing values render as n/a rather than 0, and an unconfigured source
answers 404 {"configured": false} without dialling anything, so "not
deployed here" never looks like an outage.

253 tests at 94% coverage against captured real fixtures; ruff and
pyright clean.

LLM-Generated: true

pyproject.toml

@@ -0,0 +1,71 @@
+[project]
+name = "dashboards"
+version = "0.1.0"
+description = "Homelab dashboards on one domain: system resources, LLM engines, and UPS battery health"
+readme = "README.md"
+requires-python = ">=3.13"
+# Deliberately small. Everything we collect is either our own agent's JSON (stdlib only,
+# see agent/host_agent.py) or an upstream Prometheus exposition parsed by our own parser
+# (src/dashboards/prom.py). No prometheus_client, no Grafana, no CDN, no bundler.
+dependencies = [
+    "fastapi>=0.143.3",
+    "httpx>=0.28.1",
+    "uvicorn[standard]>=0.54.0",
+    "pydantic>=2.14.1",
+    "python-dotenv>=1.2.4",
+]
+
+[dependency-groups]
+dev = [
+    "pytest>=9.1.1",
+    "pytest-cov>=7.1.0",
+    "pytest-asyncio>=1.4.0",
+    "ruff>=0.17.1",
+    "pyright>=1.1.414",
+    "debugpy>=1.8.22",
+]
+
+# Installed editable by `uv sync` (src layout), so `uv run dashboards` and
+# `uv run uvicorn dashboards.app:app` both work without PYTHONPATH gymnastics.
+[build-system]
+requires = ["hatchling>=1.27"]
+build-backend = "hatchling.build"
+
+[project.scripts]
+dashboards = "dashboards.__main__:main"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/dashboards"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+addopts = "-q --strict-markers"
+# auto: async tests run without a decorator on every single one
+asyncio_mode = "auto"
+filterwarnings = ["error::DeprecationWarning"]
+
+[tool.coverage.run]
+source = ["src/dashboards"]
+omit = ["tests/*"]
+
+[tool.coverage.report]
+show_missing = true
+skip_covered = false
+
+[tool.ruff]
+line-length = 110
+target-version = "py313"
+src = ["src", "tests", "agent"]
+
+[tool.ruff.lint]
+select = ["E", "F", "W", "I", "UP", "B", "C4", "SIM", "RUF", "BLE", "PLC"]
+ignore = ["E501"]
+
+[tool.ruff.lint.per-file-ignores]
+# FastAPI's dependency injection is a call in a default argument; that is the API, not a bug.
+"src/dashboards/api.py" = ["B008"]
+
+[tool.pyright]
+include = ["src", "tests"]
+pythonVersion = "3.13"
+typeCheckingMode = "standard"