fix: optimize Dockerfile layer caching and add .dockerignore

Separate dependency install from app code so code changes don't retrigger
full pip install. Add .dockerignore to exclude .git, tests, and results
from build context.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

.dockerignore

@@ -0,0 +1,10 @@
+.git
+.github
+results
+tests
+docs
+__pycache__
+*.pyc
+*.db
+*.egg-info
+.pytest_cache

Dockerfile

@@ -2,22 +2,42 @@ FROM python:3.11-slim
 
 WORKDIR /app
 
+# System libs for GEOS/PROJ (required by cartopy, geopandas, pyproj)
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libgeos-dev \
     libproj-dev \
     proj-data \
     proj-bin \
+    g++ \
     && rm -rf /var/lib/apt/lists/*
 
-# Install dependencies as binary wheels (fast, no compilation)
+# Layer 1: Install ALL dependencies (cached unless pyproject.toml changes)
 COPY pyproject.toml .
-COPY app/__init__.py app/__init__.py
-RUN pip install --no-cache-dir --only-binary :all: \
-    numpy scipy matplotlib cartopy geopandas shapely pyproj rioxarray xarray \
-    && pip install --no-cache-dir .
+RUN pip install --no-cache-dir --prefer-binary \
+    "fastapi>=0.110.0" \
+    "uvicorn[standard]>=0.27.0" \
+    "aiosqlite>=0.20.0" \
+    "pydantic>=2.6.0" \
+    "httpx>=0.27.0" \
+    "pystac-client>=0.7.0" \
+    "stackstac>=0.5.0" \
+    "xarray>=2024.1.0" \
+    "numpy>=1.24.0" \
+    "rioxarray>=0.15.0" \
+    "geopandas>=0.14.0" \
+    "shapely>=2.0.0" \
+    "pyproj>=3.6.0" \
+    "matplotlib>=3.8.0" \
+    "cartopy>=0.22.0" \
+    "reportlab>=4.1.0" \
+    "scipy>=1.12.0" \
+    "tqdm>=4.66.0"
 
-# Copy application code
+# Layer 2: Install app package (no-deps, just makes app/ importable)
 COPY app/ app/
+RUN pip install --no-cache-dir --no-deps .
+
+# Layer 3: Frontend (changes most often, cached separately)
 COPY frontend/ frontend/
 
 RUN mkdir -p data results