feat: Add Streamlit dashboard with Blueprint compliance (v2.1.0)

Dashboard Features:
- 8 navigation sections: Overview, Outcomes, Poor CX, FCR, Churn, Agent, Call Explorer, Export
- Beyond Brand Identity styling (colors #6D84E3, Outfit font)
- RCA Sankey diagram (Driver → Outcome → Churn Risk flow)
- Correlation heatmaps (driver co-occurrence, driver-outcome)
- Outcome Deep Dive (root causes, correlation, duration analysis)
- Export functionality (Excel, HTML, JSON)

Blueprint Compliance:
- FCR: 4 categories (Primera Llamada/Rellamada × Sin/Con Riesgo de Fuga)
- Churn: Binary view (Sin Riesgo de Fuga / En Riesgo de Fuga)
- Agent: Talento Para Replicar / Oportunidades de Mejora
- Fixed FCR rate calculation (only FIRST_CALL counts as success)

Technical:
- Streamlit + Plotly for interactive visualizations
- Light theme configuration (.streamlit/config.toml)
- Fixed Plotly colorbar titlefont deprecation

Documentation:
- Updated PROJECT_CONTEXT.md, TODO.md, CHANGELOG.md
- Added 4 new technical decisions (TD-014 to TD-017)
- Created TROUBLESHOOTING.md with 10 common issues

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,53 @@
+"""
+CXInsights - Pytest Configuration and Fixtures
+"""
+
+import os
+from pathlib import Path
+
+import pytest
+
+# Set test environment
+os.environ["TESTING"] = "true"
+
+
+@pytest.fixture
+def project_root() -> Path:
+    """Return the project root directory."""
+    return Path(__file__).parent.parent
+
+
+@pytest.fixture
+def fixtures_dir(project_root: Path) -> Path:
+    """Return the fixtures directory."""
+    return project_root / "tests" / "fixtures"
+
+
+@pytest.fixture
+def sample_audio_dir(fixtures_dir: Path) -> Path:
+    """Return the sample audio directory."""
+    return fixtures_dir / "sample_audio"
+
+
+@pytest.fixture
+def sample_transcripts_dir(fixtures_dir: Path) -> Path:
+    """Return the sample transcripts directory."""
+    return fixtures_dir / "sample_transcripts"
+
+
+@pytest.fixture
+def config_dir(project_root: Path) -> Path:
+    """Return the config directory."""
+    return project_root / "config"
+
+
+@pytest.fixture
+def taxonomy_path(config_dir: Path) -> Path:
+    """Return the RCA taxonomy file path."""
+    return config_dir / "rca_taxonomy.yaml"
+
+
+@pytest.fixture
+def settings_path(config_dir: Path) -> Path:
+    """Return the settings file path."""
+    return config_dir / "settings.yaml"