Initial import of NavSea pbf project

RUNNING.md

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+# Running the weather pipeline
+
+## Python
+
+Use `python3`. This workspace does not provide a `python` shim.
+After installing dependencies in the project virtual environment, prefer `.venv/bin/python`.
+
+## Required packages
+
+Install:
+
+```bash
+python3 -m venv .venv
+.venv/bin/pip install -r requirements.txt
+```
+
+The pipeline requires these runtime dependencies:
+
+- `requests`
+- `numpy`
+- `xarray`
+- `cfgrib`
+- `eccodes`
+- `mercantile`
+- `mapbox-vector-tile`
+
+## Commands
+
+Run the full pipeline:
+
+```bash
+.venv/bin/python src/weather_pipeline.py
+```
+
+Run individual steps:
+
+```bash
+.venv/bin/python src/gfs_downloader.py
+.venv/bin/python src/grid_builder_v2.py
+.venv/bin/python src/vector_tile_generator.py
+```
+
+Wave fields in the weather tiles come from the downloader and grid builder. If you want `wh`/`wdir`/`wp` to contain real data instead of compatibility zeros from older grid JSON, rerun the downloader before rebuilding grids and tiles.
+
+The weather tile generator now builds `z=2,4,6,8,10,12` by default so wind barb density stays usable after zooming in. If you need a custom set, override with `WEATHER_TILE_ZOOMS`, for example:
+
+```bash
+WEATHER_TILE_ZOOMS=2,4,6,8,10,12,14 .venv/bin/python src/vector_tile_generator.py
+```
+
+## Known environment blockers in this session
+
+- Network access may prevent `src/gfs_downloader.py` from reaching NOAA.