Build the SvelteKit frontend: calm home with mood modes

- New frontend/ SvelteKit static SPA (Svelte 5), served by FastAPI from
  frontend/build (falls back to the legacy page if unbuilt).
- Calm design system: cream/sage palette, serif headlines, generous space,
  no urgency colors, gentle motion (respects prefers-reduced-motion).
- Home screen: mood-mode nav (Today/Wonder/People Helping/Solutions/Light
  Only/Grounded), the daily brief as a hero + remaining four, browsable mood
  lanes, an explicit calm end-state, inline Not today / Less like this / Hide
  affordances, and device-local Calm Filters mirroring goodnews/filters.py.
- Backend: moods.py + GET /api/moods (single source of truth for the modes);
  FilterPrefs gains max_cortisol/max_ragebait ceilings (for Light Only).
- Push categorical filters (include/mute topics+flavors, ceilings) into SQL in
  queries.feed so low-ranked-but-matching items (e.g. discovery for Wonder)
  are not truncated by ranking; only avoid-terms stay a Python pass.
- PWA manifest + icon (installable; offline deferred per plan).
- Multi-stage Dockerfile builds the site then serves it from the API.
- Tests: queries.feed categorical filters (63 total). README updated.

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

goodnews/queries.py

@@ -47,8 +47,20 @@ def feed(
     accepted_only: bool = True,
     limit: int = 30,
     offset: int = 0,
+    include_topics: list[str] | None = None,
+    include_flavors: list[str] | None = None,
+    mute_topics: list[str] | None = None,
+    mute_flavors: list[str] | None = None,
+    max_cortisol: int | None = None,
+    max_ragebait: int | None = None,
 ) -> list[dict]:
-    """Return ranked articles, optionally filtered by topic and/or flavor."""
+    """Return ranked articles with categorical filters applied in SQL.
+
+    Categorical filters (topic/flavor include & mute, cortisol/ragebait ceilings)
+    must be applied here, not after ranking — otherwise low-ranked-but-matching
+    items (e.g. 'discovery' for a Wonder lane) fall outside any over-fetch window.
+    Word-boundary avoid-terms remain a Python pass on the caller side.
+    """
     clauses = ["a.duplicate_of IS NULL"]
     params: list = []
     if accepted_only:
@@ -59,7 +71,31 @@ def feed(
     if flavor:
         clauses.append("s.flavor = ?")
         params.append(flavor.lower())
-    where = ("WHERE " + " AND ".join(clauses)) if clauses else ""
+
+    def _in(column: str, values: list[str], negate: bool = False) -> None:
+        vals = [v.lower() for v in values]
+        placeholders = ",".join("?" * len(vals))
+        op = "NOT IN" if negate else "IN"
+        # COALESCE keeps NULL-category rows from being dropped by NOT IN.
+        clauses.append(f"COALESCE({column}, '') {op} ({placeholders})")
+        params.extend(vals)
+
+    if include_topics:
+        _in("s.topic", include_topics)
+    if include_flavors:
+        _in("s.flavor", include_flavors)
+    if mute_topics:
+        _in("s.topic", mute_topics, negate=True)
+    if mute_flavors:
+        _in("s.flavor", mute_flavors, negate=True)
+    if max_cortisol is not None:
+        clauses.append("COALESCE(s.cortisol_score, 0) <= ?")
+        params.append(max_cortisol)
+    if max_ragebait is not None:
+        clauses.append("COALESCE(s.ragebait_score, 0) <= ?")
+        params.append(max_ragebait)
+
+    where = "WHERE " + " AND ".join(clauses)
     params.extend([limit, offset])
 
     rows = conn.execute(