Add readme for map production/storage

Author: jdahren

scripts/report_maps/pba50_plus/.gitignore

@@ -0,0 +1,24 @@
+# Ignore large data and output files
+map_data/
+parcel_data/
+
+# Geospatial file formats
+*.gpkg
+*.shp
+*.shx
+*.dbf
+*.prj
+*.cpg
+*.sbx
+*.sbn
+
+# ArcGIS files
+*.aprx
+*.gdb/
+*.tbx
+
+# Large CSV files (if needed, can be more specific)
+# *.csv
+
+# Track only Python scripts
+!*.py

scripts/report_maps/pba50_plus/README.md

@@ -0,0 +1,34 @@
+# PBA50+ Modeling Report Maps
+
+This directory contains scripts and data for generating supplementary map layers for the PBA50+ Forecasting and Modeling Report.
+
+## Setup
+
+### First-time setup:
+
+1. **Clone the repo**
+   ```bash
+   git clone https://github.com/BayAreaMetro/bayarea_urbansim.git
+   cd bayarea_urbansim/scripts/report_maps/pba50_plus
+   ```
+
+2. **Download large files from Box**
+   - Box folder: https://mtcdrive.app.box.com/folder/363365649386
+   - Download the contents of the `pba50_plus` folder
+   - Copy the Box contents into your local `pba50_plus` directory
+
+3. **Run the map preparation script**
+   ```bash
+   cd Python
+   python prep_map_layers.py
+   ```
+
+## File Storage
+
+- **Git**: Python scripts
+- **Box**: Large data files, map outputs, ArcGIS project files
+  - Link: https://mtcdrive.app.box.com/folder/363365649386
+
+## Output
+
+The `prep_map_layers.py` script generates map layers in the `map_data/` directory that can be loaded into ArcGIS Pro for mapping. `map_data/FBP_Discrete_Modeling_GG_v3` contains GG shapefiles that were provided by Mark Shorett, originally from [here](https://mtcdrive.app.box.com/file/1877520162335?s=ohnpzgetvztmjt1t13nzw266ph1ezyro).