feat: Add reviewiq-pipeline package for LLM-powered review classification

Implement a standalone Python package for processing customer reviews through
a 4-stage pipeline using URT (Universal Review Taxonomy) v5.1:

- Stage 1: Normalization (text cleaning, language detection, deduplication)
- Stage 2: LLM Classification (OpenAI/Anthropic span extraction with URT codes)
- Stage 3: Issue Routing (deterministic issue ID generation, span linking)
- Stage 4: Fact Aggregation (time series metrics for dashboards)

Package includes:
- TypedDict contracts matching Pipeline-Contracts-v1.md
- Async database layer with asyncpg and 5 SQL migrations
- LLM client abstraction supporting both OpenAI and Anthropic
- Sentence-transformers integration for embeddings
- Validation rules V1.x through V4.x
- CLI commands: migrate, run, validate, check
- 55 unit and integration tests (all passing)

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

packages/reviewiq-pipeline/src/reviewiq_pipeline/__init__.py

@@ -0,0 +1,56 @@
+"""
+ReviewIQ Pipeline - LLM-powered review classification and analysis.
+
+This package provides a complete pipeline for processing customer reviews:
+- Stage 1: Normalization (text cleaning, language detection, deduplication)
+- Stage 2: LLM Classification (span extraction with URT codes)
+- Stage 3: Issue Routing (route negative spans to issues)
+- Stage 4: Fact Aggregation (pre-aggregate metrics for dashboards)
+"""
+
+from reviewiq_pipeline.config import Config
+from reviewiq_pipeline.contracts import (
+    ClassifiedReview,
+    ExtractedSpan,
+    FactRecord,
+    NormalizedReview,
+    RawReview,
+    RoutedSpan,
+    ScraperOutput,
+    Stage1Input,
+    Stage1Output,
+    Stage2Input,
+    Stage2Output,
+    Stage3Input,
+    Stage3Output,
+    Stage4Input,
+    Stage4Output,
+    ValidationError,
+    ValidationResult,
+)
+from reviewiq_pipeline.pipeline import Pipeline
+
+__version__ = "0.1.0"
+__all__ = [
+    # Main API
+    "Pipeline",
+    "Config",
+    # Contracts
+    "ScraperOutput",
+    "RawReview",
+    "Stage1Input",
+    "Stage1Output",
+    "NormalizedReview",
+    "Stage2Input",
+    "Stage2Output",
+    "ClassifiedReview",
+    "ExtractedSpan",
+    "Stage3Input",
+    "Stage3Output",
+    "RoutedSpan",
+    "Stage4Input",
+    "Stage4Output",
+    "FactRecord",
+    "ValidationResult",
+    "ValidationError",
+]