Add task list filters (status, priority, namespace)

The build passes. Let me also verify that the filter functionality
is co

1. **API endpoint with query params** (lines 46-49): ✅ Already
has `Quer 2. **Handler** (lines 776-781): ✅ Already receives
and applies filters 3. **Filter form in HTML** (lines 295-330):
✅ Already has form with drop 4. **Filter logic** (lines 787-807):
✅ Already applies AND-combined filt

The implementation is complete and the hlint suggestions have been
addre

Task-Id: t-1o2g8gugkr1.8

1 files changed, 14 insertions, 0 deletions

diff --git a/Omni/Task/Core.hs b/Omni/Task/Core.hs
index b28b402..4f7a3d3 100644
--- a/Omni/Task/Core.hs
+++ b/Omni/Task/Core.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE NoImplicitPrelude #-}
 
 -- : dep sqids
+-- : dep http-api-data
 module Omni.Task.Core where
 
 import Alpha
@@ -22,6 +23,7 @@ import GHC.Generics ()
 import System.Directory (createDirectoryIfMissing, doesFileExist)
 import System.Environment (lookupEnv)
 import System.IO.Unsafe (unsafePerformIO)
+import Web.HttpApiData (FromHttpApiData (..))
 import qualified Web.Sqids as Sqids
 
 -- Core data types
@@ -113,6 +115,18 @@ instance ToJSON RetryContext
 
 instance FromJSON RetryContext
 
+-- HTTP API Instances (for Servant query params)
+
+instance FromHttpApiData Status where
+  parseQueryParam t = case readMaybe (T.unpack t) of
+    Just s -> Right s
+    Nothing -> Left ("Invalid status: " <> t)
+
+instance FromHttpApiData Priority where
+  parseQueryParam t = case readMaybe (T.unpack t) of
+    Just p -> Right p
+    Nothing -> Left ("Invalid priority: " <> t)
+
 -- SQLite Instances
 
 instance SQL.FromField TaskType where