ci: enforce 80% coverage gate and improve repo hygiene

- Add --cov-fail-under=80 gate to pytest addopts
- Enable pip cache and job concurrency (cancel in-progress) in CI
- Add dependabot for pip and GitHub Actions
- Switch to SPDX license expression
- Wrap Streamlit app entry in main() guarded by __name__ to make it importable
- Add app-entry smoke test and merge test_load_data into test_data (dedup)
- Add .gitattributes for LF normalization and binary png markers

Author: alvarosalinaso

.gitattributes

@@ -0,0 +1,6 @@
+# Normalizar saltos de línea a LF en texto, mantener binarios intactos
+* text=auto
+
+*.png binary
+*.jpg binary
+*.csv text eol=lf

.github/dependabot.yml

@@ -0,0 +1,13 @@
+version: 2
+updates:
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 5

.github/workflows/ci.yml

@@ -6,6 +6,10 @@ on:
   pull_request:
     branches: [ main ]
 
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -16,6 +20,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: "3.12"
+          cache: pip
 
       - name: Install dependencies
         run: |
@@ -41,13 +46,14 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
+          cache: pip
 
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install -e ".[dev]"
 
-      - name: Run tests
+      - name: Run tests (coverage gate >=80%)
         run: pytest
 
       - name: Upload coverage report