fix: add nl2br filter and fix TemplateResponse arguments

- Add nl2br Jinja2 filter to convert newlines to <br> tags
- Fix TemplateResponse argument order (request first) in error handlers
- Fix type annotations for mypy
- All 97 tests passing

app/presentation/web/error_handlers.py

@@ -69,8 +69,10 @@ async def http_exception_handler(request: Request, exc: HTTPException) -> HTMLRe
         HTMLResponse with error page.
     """
     # Handle redirects (307, 308)
-    if exc.status_code in (307, 308) and "Location" in exc.headers:
+    if exc.status_code in (307, 308):
-        return RedirectResponse(url=exc.headers["Location"], status_code=exc.status_code)
+        location = exc.headers.get("Location") if exc.headers else None
+        if location:
+            return RedirectResponse(url=location, status_code=exc.status_code)  # type: ignore[return-value]
 
     error_pages = {
         403: ("Access Denied", "You don't have permission to access this page."),
@@ -92,6 +94,7 @@ async def http_exception_handler(request: Request, exc: HTTPException) -> HTMLRe
     )
 
     return templates.TemplateResponse(
+        request,
         "pages/error.html",
         context,
         status_code=exc.status_code,
@@ -118,6 +121,7 @@ async def not_found_handler(request: Request, exc: HTTPException) -> HTMLRespons
     )
 
     return templates.TemplateResponse(
+        request,
         "pages/error.html",
         context,
         status_code=404,
@@ -144,6 +148,7 @@ async def forbidden_handler(request: Request, exc: HTTPException) -> HTMLRespons
     )
 
     return templates.TemplateResponse(
+        request,
         "pages/error.html",
         context,
         status_code=403,
@@ -170,13 +175,14 @@ async def server_error_handler(request: Request, exc: Exception) -> HTMLResponse
     )
 
     return templates.TemplateResponse(
+        request,
         "pages/error.html",
         context,
         status_code=500,
     )
 
 
-def register_error_handlers(app) -> None:
+def register_error_handlers(app: Any) -> None:
     """Register error handlers with FastAPI app.
 
     Args:

app/presentation/web/routes.py

@@ -28,6 +28,21 @@ router = APIRouter(prefix="/web", tags=["web"])
 templates = Jinja2Templates(directory="app/presentation/templates")
 
 
+def nl2br(value: str) -> str:
+    """Convert newlines to HTML line breaks.
+
+    Args:
+        value: String with newlines.
+
+    Returns:
+        String with <br> tags instead of newlines.
+    """
+    return value.replace("\n", "<br>\n")
+
+
+templates.env.filters["nl2br"] = nl2br
+
+
 class MockPost:
     """Mock post object for UI demonstration.