Calm Filters MVP: device-local personalization across feed/brief/counts

- API endpoints (feed, brief, category-counts) accept a 'prefs' JSON query
  param, parsed tolerantly into FilterPrefs (bad blobs never break the feed).
- Feed over-fetches then applies word-boundary filters in Python and slices to
  the page; brief is filtered down (no refill); counts are computed over the
  same filtered set so browse numbers match the feed exactly.
- Pause.active() coerces naive datetimes to UTC; FilterPrefs.from_dict skips
  malformed pauses and non-string list entries.
- Static site adds the humane ladder (Not today / Less like this / Always hide)
  plus a Calm filters panel managing pauses, mutes, and avoid-terms in
  localStorage. Nothing leaves the device.
- Tests now 38 (added forgiving-parse and naive-now cases). README documents it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_filters.py

@@ -4,6 +4,7 @@ from goodnews.filters import (
     FilterPrefs,
     Pause,
     filter_articles,
+    prefs_from_json,
     text_matches_avoid_terms,
 )
 
@@ -86,3 +87,37 @@ def test_pause_active_helper():
     assert Pause("topic", "health", "2026-06-02T00:00:00Z").active(NOW)
     assert not Pause("topic", "health", "2026-05-01T00:00:00Z").active(NOW)
     assert not Pause("topic", "health", "garbage").active(NOW)
+
+
+def test_pause_active_tolerates_naive_now():
+    # A naive `now` must not raise an aware-vs-naive comparison error.
+    naive = datetime(2026, 6, 1)
+    assert Pause("topic", "health", "2026-06-02T00:00:00Z").active(naive)
+
+
+# --- forgiving parsing (bad blobs must never break the feed) ---
+
+def test_prefs_from_json_tolerates_garbage():
+    assert prefs_from_json("not json").is_empty()
+    assert prefs_from_json(None).is_empty()
+    assert prefs_from_json("[1,2,3]").is_empty()  # wrong shape
+
+
+def test_from_dict_skips_malformed_pauses():
+    prefs = FilterPrefs.from_dict(
+        {
+            "mute_topics": ["health"],
+            "pauses": [
+                {"kind": "topic", "value": "science", "until": "2026-06-02T00:00:00Z"},
+                {"kind": "topic"},  # malformed — missing value/until
+                "garbage",            # not even a dict
+            ],
+        }
+    )
+    assert prefs.mute_topics == ["health"]
+    assert len(prefs.pauses) == 1  # only the well-formed pause survives
+
+
+def test_from_dict_ignores_non_string_list_entries():
+    prefs = FilterPrefs.from_dict({"avoid_terms": ["ok", 5, None, "fine"]})
+    assert prefs.avoid_terms == ["ok", "fine"]