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>

infra/supervisor/supervisor.sh

@@ -24,9 +24,14 @@ do
         git switch --discard-changes --detach origin/master
         uv sync
 
-        # Run pipelines (SQLMesh handles scheduling)
-        #uv run materia pipeline run extract
-        #uv run materia pipeline run transform
+        # Run pipelines
+        LANDING_DIR="${LANDING_DIR:-/data/materia/landing}" \
+        DUCKDB_PATH="${DUCKDB_PATH:-/data/materia/lakehouse.duckdb}" \
+            uv run materia pipeline run extract
+
+        LANDING_DIR="${LANDING_DIR:-/data/materia/landing}" \
+        DUCKDB_PATH="${DUCKDB_PATH:-/data/materia/lakehouse.duckdb}" \
+            uv run materia pipeline run transform
 
     ) || sleep 600  # Sleep 10 min on failure to avoid busy-loop retries
 done