fix: критические баги и качество кода — полный аудит

Критические фиксы:
- main.py: монтировать /static из web/static/ (CSS не грузился совсем)
- api/scans.py: filtered total count (был всегда общий, игнорируя фильтры)
- web/routes.py: исправлен VALID_SORT_FIELDS (отсутствовали ключи packages)
- web/routes.py: filtered total count для web scans list
- package_detail.html: f.data.X вместо f.X (findings не отображались)

Чистка мёртвого кода:
- config.py: удалён _parse_repos и nexus_repositories (не использовались)
- web/routes.py: удалён completed_scans/failed_scans (не отображались)
- удалён мёртвый guarddog_nexus/static/style.css (67-байтный стаб)

Качество кода:
- web/routes.py: Jinja2 Environment кэшируется на уровне модуля
- Вынесен дублирующийся JS в web/static/app.js
- Вынесены дублирующиеся inline-стили в CSS-классы
- Исправлен duplicate class attribute в списках
- Удалены гигантские SVG из empty states

Тесты:
- 20 новых edge-case тестов (CSV export, search/filter/sort, 404, pagination)
- Добавлен sample_flagged_scan fixture
- Итого: 50 тестов, все зелёные

guarddog_nexus/web/routes.py

@@ -4,6 +4,7 @@ import datetime
 
 from fastapi import APIRouter, Depends, Request
 from fastapi.responses import HTMLResponse
+from jinja2 import Environment, PackageLoader, select_autoescape
 from sqlalchemy import Integer, cast, func, select, text
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -12,7 +13,12 @@ from guarddog_nexus.models import Finding, Scan
 
 router = APIRouter(tags=["web"])
 
-VALID_SORT_FIELDS = {
+_jinja_env = Environment(
+    loader=PackageLoader("guarddog_nexus", "web/templates"),
+    autoescape=select_autoescape(),
+)
+
+SCAN_SORT_FIELDS = {
     "id": Scan.id,
     "package_name": Scan.package_name,
     "started_at": Scan.started_at,
@@ -20,15 +26,16 @@ VALID_SORT_FIELDS = {
     "total_findings": Scan.total_findings,
 }
 
+PACKAGE_SORT_FIELDS = {
+    "name": Scan.package_name,
+    "last_scanned_at": Scan.started_at,
+    "total_findings": Scan.total_findings,
+    "flagged": Scan.flagged,
+}
+
 
 def _render(name: str, **context) -> HTMLResponse:
-    from jinja2 import Environment, PackageLoader, select_autoescape
-
-    env = Environment(
-        loader=PackageLoader("guarddog_nexus", "web/templates"),
-        autoescape=select_autoescape(),
-    )
-    template = env.get_template(name)
+    template = _jinja_env.get_template(name)
     return HTMLResponse(template.render(**context))
 
 
@@ -53,10 +60,6 @@ async def _dashboard_data(session: AsyncSession) -> dict:
             Scan.started_at >= func.datetime("now", "-7 days"),
         )
     )
-    completed_scans = await session.scalar(
-        select(func.count(Scan.id)).where(Scan.status == "completed")
-    )
-    failed_scans = await session.scalar(select(func.count(Scan.id)).where(Scan.status == "failed"))
     total_findings = await session.scalar(select(func.count(Finding.id)))
 
     warnings_count = await session.scalar(
@@ -115,7 +118,6 @@ async def _dashboard_data(session: AsyncSession) -> dict:
 
     max_findings = max((r.total for r in most_flagged), default=1)
 
-    # Heatmap: scans per day for last 14 days
     days_raw = (
         await session.execute(
             select(
@@ -133,8 +135,6 @@ async def _dashboard_data(session: AsyncSession) -> dict:
         "total_scans": total_scans or 0,
         "flagged_scans": flagged_scans or 0,
         "recent_flagged": recent_flagged or 0,
-        "completed_scans": completed_scans or 0,
-        "failed_scans": failed_scans or 0,
         "total_findings": total_findings or 0,
         "warnings_count": warnings_count or 0,
         "errors_count": errors_count or 0,
@@ -162,23 +162,27 @@ async def scans_list(
     per_page = 50
     offset = (page - 1) * per_page
 
+    count_q = select(func.count(Scan.id))
     q = select(Scan)
+
     if flagged == "1":
         q = q.where(Scan.flagged == True)
+        count_q = count_q.where(Scan.flagged == True)
     if status:
         q = q.where(Scan.status == status)
+        count_q = count_q.where(Scan.status == status)
     if search:
         pattern = f"%{search}%"
-        q = q.where(
-            Scan.package_name.ilike(pattern) | Scan.package_version.ilike(pattern)
-        )
+        condition = Scan.package_name.ilike(pattern) | Scan.package_version.ilike(pattern)
+        q = q.where(condition)
+        count_q = count_q.where(condition)
 
-    sort_field = VALID_SORT_FIELDS.get(sort_by, Scan.started_at)
+    sort_field = SCAN_SORT_FIELDS.get(sort_by, Scan.started_at)
     q = q.order_by(sort_field.desc() if sort_dir == "desc" else sort_field.asc())
     q = q.offset(offset).limit(per_page)
 
     scans = (await session.execute(q)).scalars().all()
-    total = await session.scalar(select(func.count(Scan.id)))
+    total = await session.scalar(count_q)
 
     return _render(
         "scans_list.html",
@@ -240,17 +244,17 @@ async def packages_list(
             Scan.package_name.ilike(pattern) | Scan.package_version.ilike(pattern)
         )
 
-    sort_field = VALID_SORT_FIELDS.get(sort_by, Scan.started_at)
+    sort_field = PACKAGE_SORT_FIELDS.get(sort_by, Scan.started_at)
     sort_col = func.max(sort_field)
     subq = subq.order_by(
         sort_col.desc() if sort_dir == "desc" else sort_col.asc()
     )
 
-    subq = subq.subquery()
-    total = await session.scalar(select(func.count()).select_from(subq))
+    sq = subq.subquery()
+    total = await session.scalar(select(func.count()).select_from(sq))
     rows = (
         await session.execute(
-            select(subq).offset(offset).limit(per_page)
+            select(sq).offset(offset).limit(per_page)
         )
     ).all()