Add "Changed Since" rate movement indicators to Market View matrix

A new toolbar row on the Rate Matrix lets users pick a reference datetime
(defaults to 24h ago, with 24h/3d/7d presets) and see ▲/▼ triangles
next to each competitor's BAR where the rate has moved ≥50p since then.

Two backend endpoints:
- GET /competitors/rate-changes?since=  — static datetime comparison
- GET /competitors/rate-changes-vs-own  — dynamic: diffs against the
  timestamp our own Newbook rate last changed per date (highlights
  competitor moves made in response to our own pricing decisions)

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

backend/api/competitors.py

@@ -1484,3 +1484,135 @@ async def get_scrape_history(
         }
         for row in result.fetchall()
     ]
+
+
+# ============================================
+# RATE CHANGE INDICATORS
+# ============================================
+
+@router.get("/rate-changes")
+async def get_rate_changes(
+    from_date: str,
+    to_date: str,
+    since: str,
+    include_market: bool = False,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """
+    For each hotel+date in the range, return the best 2-adult available rate
+    at the most recent scrape before `since`. The frontend diffs this against
+    the current rate to show ▲/▼ movement indicators.
+    """
+    try:
+        start = date.fromisoformat(from_date)
+        end = date.fromisoformat(to_date)
+        since_dt = datetime.fromisoformat(since.replace('Z', '+00:00'))
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=f"Invalid date format: {e}")
+
+    if (end - start).days > 90:
+        raise HTTPException(status_code=400, detail="Date range cannot exceed 90 days")
+
+    tier_filter = "h.tier IN ('own', 'competitor')"
+    if include_market:
+        tier_filter = "h.tier IN ('own', 'competitor', 'market')"
+
+    result = await db.execute(
+        text(f"""
+            SELECT DISTINCT ON (r.hotel_id, r.rate_date)
+                r.hotel_id,
+                r.rate_date,
+                r.rate_gross  AS prev_rate,
+                r.scraped_at  AS prev_scraped_at
+            FROM booking_com_rates r
+            JOIN booking_com_hotels h ON r.hotel_id = h.id
+            WHERE {tier_filter}
+              AND h.is_active = TRUE
+              AND r.rate_date >= :from_date AND r.rate_date <= :to_date
+              AND r.scraped_at <= :since
+              AND r.availability_status = 'available'
+              AND r.rate_gross IS NOT NULL
+              AND (r.max_persons IS NULL OR r.max_persons = 0 OR r.max_persons = 2)
+            ORDER BY r.hotel_id, r.rate_date,
+                CASE WHEN r.max_persons IS NULL OR r.max_persons = 0 OR r.max_persons = 2 THEN 0 ELSE 1 END,
+                r.scraped_at DESC,
+                r.rate_gross ASC NULLS LAST
+        """),
+        {'from_date': start, 'to_date': end, 'since': since_dt},
+    )
+
+    out: Dict[int, Dict[str, dict]] = {}
+    for row in result.fetchall():
+        out.setdefault(row.hotel_id, {})[row.rate_date.isoformat()] = {
+            'prev_rate': float(row.prev_rate),
+            'prev_scraped_at': row.prev_scraped_at.isoformat() if row.prev_scraped_at else None,
+        }
+    return out
+
+
+@router.get("/rate-changes-vs-own")
+async def get_rate_changes_vs_own(
+    from_date: str,
+    to_date: str,
+    include_market: bool = False,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """
+    For each competitor hotel+date, return the best 2-adult available rate
+    at the time our own Newbook rate last changed for that date. Shows whether
+    competitors moved their rates after we last updated ours.
+    """
+    try:
+        start = date.fromisoformat(from_date)
+        end = date.fromisoformat(to_date)
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=f"Invalid date format: {e}")
+
+    if (end - start).days > 90:
+        raise HTTPException(status_code=400, detail="Date range cannot exceed 90 days")
+
+    tier_filter = "h.tier IN ('own', 'competitor')"
+    if include_market:
+        tier_filter = "h.tier IN ('own', 'competitor', 'market')"
+
+    result = await db.execute(
+        text(f"""
+            SELECT DISTINCT ON (r.hotel_id, r.rate_date)
+                r.hotel_id,
+                r.rate_date,
+                r.rate_gross      AS prev_rate,
+                r.scraped_at      AS prev_scraped_at,
+                own.own_last_changed
+            FROM booking_com_rates r
+            JOIN booking_com_hotels h ON r.hotel_id = h.id
+            JOIN (
+                SELECT rate_date, MAX(valid_from) AS own_last_changed
+                FROM newbook_current_rates
+                WHERE rate_date >= :from_date AND rate_date <= :to_date
+                GROUP BY rate_date
+            ) own ON r.rate_date = own.rate_date
+            WHERE {tier_filter}
+              AND h.is_active = TRUE
+              AND r.rate_date >= :from_date AND r.rate_date <= :to_date
+              AND r.scraped_at <= own.own_last_changed
+              AND r.availability_status = 'available'
+              AND r.rate_gross IS NOT NULL
+              AND (r.max_persons IS NULL OR r.max_persons = 0 OR r.max_persons = 2)
+            ORDER BY r.hotel_id, r.rate_date,
+                CASE WHEN r.max_persons IS NULL OR r.max_persons = 0 OR r.max_persons = 2 THEN 0 ELSE 1 END,
+                r.scraped_at DESC,
+                r.rate_gross ASC NULLS LAST
+        """),
+        {'from_date': start, 'to_date': end},
+    )
+
+    out: Dict[int, Dict[str, dict]] = {}
+    for row in result.fetchall():
+        out.setdefault(row.hotel_id, {})[row.rate_date.isoformat()] = {
+            'prev_rate': float(row.prev_rate),
+            'prev_scraped_at': row.prev_scraped_at.isoformat() if row.prev_scraped_at else None,
+            'own_last_changed': row.own_last_changed.isoformat() if row.own_last_changed else None,
+        }
+    return out