feat(affiliate): migration 0026 — affiliate_products + affiliate_clicks tables

Adds affiliate product catalog and click tracking tables.
UNIQUE(slug, language) mirrors articles schema for multi-language support.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/padelnomics/migrations/versions/0026_affiliate_products.py

@@ -0,0 +1,65 @@
+"""Migration 0026: Affiliate product catalog + click tracking tables.
+
+affiliate_products: admin-managed product catalog for editorial affiliate cards.
+  - slug+language uniqueness mirrors articles (same slug can exist in DE + EN
+    with different affiliate URLs, copy, and pros/cons).
+  - retailer: display name (Amazon, Padel Nuestro, etc.) — stored in full URL
+    with tracking params already baked into affiliate_url.
+  - cta_label: per-product override; empty → use i18n default "Zum Angebot".
+  - status: draft/active/archived — only active products are baked into articles.
+
+affiliate_clicks: one row per /go/<slug> redirect hit.
+  - ip_hash: SHA256(ip + YYYY-MM-DD + SECRET_KEY[:16]), daily rotation for GDPR.
+  - article_slug: best-effort extraction from Referer header.
+"""
+
+
+def up(conn) -> None:
+    conn.execute("""
+        CREATE TABLE affiliate_products (
+            id            INTEGER PRIMARY KEY AUTOINCREMENT,
+            slug          TEXT NOT NULL,
+            name          TEXT NOT NULL,
+            brand         TEXT NOT NULL DEFAULT '',
+            category      TEXT NOT NULL DEFAULT 'accessory',
+            retailer      TEXT NOT NULL DEFAULT '',
+            affiliate_url TEXT NOT NULL,
+            image_url     TEXT NOT NULL DEFAULT '',
+            price_cents   INTEGER,
+            currency      TEXT NOT NULL DEFAULT 'EUR',
+            rating        REAL,
+            pros          TEXT NOT NULL DEFAULT '[]',
+            cons          TEXT NOT NULL DEFAULT '[]',
+            description   TEXT NOT NULL DEFAULT '',
+            cta_label     TEXT NOT NULL DEFAULT '',
+            status        TEXT NOT NULL DEFAULT 'draft',
+            language      TEXT NOT NULL DEFAULT 'de',
+            sort_order    INTEGER NOT NULL DEFAULT 0,
+            created_at    TEXT NOT NULL DEFAULT (datetime('now')),
+            updated_at    TEXT,
+            UNIQUE(slug, language)
+        )
+    """)
+    conn.execute("""
+        CREATE TABLE affiliate_clicks (
+            id           INTEGER PRIMARY KEY AUTOINCREMENT,
+            product_id   INTEGER NOT NULL REFERENCES affiliate_products(id),
+            article_slug TEXT,
+            referrer     TEXT,
+            ip_hash      TEXT NOT NULL,
+            clicked_at   TEXT NOT NULL DEFAULT (datetime('now'))
+        )
+    """)
+    # Queries: products by category+status, clicks by product and time
+    conn.execute(
+        "CREATE INDEX idx_affiliate_products_category_status"
+        " ON affiliate_products(category, status)"
+    )
+    conn.execute(
+        "CREATE INDEX idx_affiliate_clicks_product_id"
+        " ON affiliate_clicks(product_id)"
+    )
+    conn.execute(
+        "CREATE INDEX idx_affiliate_clicks_clicked_at"
+        " ON affiliate_clicks(clicked_at)"
+    )