Refactor to local-first architecture on Hetzner NVMe

Remove distributed R2/Iceberg/SSH pipeline architecture in favor of
local subprocess execution with NVMe storage. Landing data backed up
to R2 via rclone timer.

- Strip Iceberg catalog, httpfs, boto3, paramiko, prefect, pyarrow
- Pipelines run via subprocess.run() with bounded timeouts
- Extract writes to {LANDING_DIR}/psd/{year}/{month}/{etag}.csv.gzip
- SQLMesh reads LANDING_DIR variable, writes to DUCKDB_PATH
- Delete unused provider stubs (ovh, scaleway, oracle)
- Add rclone systemd timer for R2 backup every 6h
- Update supervisor to run pipelines with env vars

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -9,14 +9,11 @@ authors = [
 ]
 requires-python = ">=3.13"
 dependencies = [
-    "pyarrow>=20.0.0",
     "python-dotenv>=1.1.0",
     "typer>=0.15.0",
-    "paramiko>=3.5.0",
     "pyyaml>=6.0.2",
     "niquests>=3.15.2",
     "hcloud>=2.8.0",
-    "prefect>=3.6.15",
 ]
 
 [project.scripts]
@@ -130,4 +127,5 @@ force-single-line = false
 # Allow print statements and other rules in scripts
 "scripts/*" = ["T201"]
 
-
+[tool.pytest.ini_options]
+testpaths = ["tests"]