ui: добавить поиск, фильтрацию и сортировку на списки

API:
- scans.py: добавить search, status, sort_by, sort_dir параметры
- packages.py: добавить search, sort_by, sort_dir параметры
- web/routes.py: передать новые параметры в шаблоны

UI:
- scans_list.html: search input (htmx debounce), status filter dropdown,
  sortable columns с hx-get, empty state
- packages_list.html: search input (htmx debounce), sortable columns,
  empty state
- pagination сохраняет все параметры фильтрации/сортировки

guarddog_nexus/api/packages.py

@@ -1,7 +1,7 @@
 """REST API for packages (distinct packages across scans)."""
 
 from fastapi import APIRouter, Depends, Query
-from sqlalchemy import func, select
+from sqlalchemy import func, select, text
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from guarddog_nexus.database import get_session
@@ -9,6 +9,14 @@ from guarddog_nexus.models import Finding, Scan
 
 router = APIRouter(prefix="/api/v1/packages", tags=["packages"])
 
+VALID_SORT_FIELDS = {
+    "name": Scan.package_name,
+    "version": Scan.package_version,
+    "last_scanned_at": Scan.started_at,
+    "total_findings": Scan.total_findings,
+    "flagged": Scan.flagged,
+}
+
 
 @router.get("")
 async def list_packages(
@@ -16,6 +24,10 @@ async def list_packages(
     offset: int = Query(0, ge=0),
     ecosystem: str | None = Query(None),
     flagged: bool | None = Query(None),
+    search: str | None = Query(None),
+    repository: str | None = Query(None),
+    sort_by: str = Query("last_scanned_at"),
+    sort_dir: str = Query("desc"),
     session: AsyncSession = Depends(get_session),
 ):
     subq = select(
@@ -33,14 +45,26 @@ async def list_packages(
         subq = subq.where(Scan.ecosystem == ecosystem)
     if flagged is not None:
         subq = subq.having(func.max(Scan.flagged) == flagged)
+    if repository:
+        subq = subq.where(Scan.repository == repository)
+    if search:
+        pattern = f"%{search}%"
+        subq = subq.where(
+            Scan.package_name.ilike(pattern) | Scan.package_version.ilike(pattern)
+        )
+
+    sort_field = VALID_SORT_FIELDS.get(sort_by, Scan.started_at)
+    sort_dir = "asc" if sort_dir.lower() == "asc" else "desc"
+    sort_col = func.max(sort_field)
+    subq = subq.order_by(
+        sort_col.desc() if sort_dir == "desc" else sort_col.asc()
+    )
 
     total_q = select(func.count()).select_from(subq.subquery())
     total = await session.scalar(total_q)
 
     rows = (
-        await session.execute(
-            subq.order_by(func.max(Scan.started_at).desc()).offset(offset).limit(limit)
-        )
+        await session.execute(subq.offset(offset).limit(limit))
     ).all()
 
     return {