Add note context visibility in chat and standardize UI design tokens

Improve chat context: build_context() now returns metadata about auto-found
notes, emitted as an SSE event so the frontend can display context pills
showing which notes influenced the response. Users can promote notes for
deeper context (+) or exclude irrelevant ones (x). A note picker lets users
manually attach notes. Multi-word search uses per-term AND matching, and
auto-search iterates keywords individually for broader OR-style coverage.

Standardize styling: introduce CSS design tokens (--radius-sm/md/lg/pill,
--color-success/warning/overlay, --focus-ring) and migrate all components
to use them. Fix header alignment to full-width, add active nav link state,
replace hardcoded colors with CSS variables, and normalize button padding.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/fabledassistant/services/notes.py

@@ -60,11 +60,13 @@ async def list_notes(
             count_query = count_query.where(Note.status.is_(None))
 
         if q:
-            escaped_q = q.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
-            pattern = f"%{escaped_q}%"
-            filter_ = or_(Note.title.ilike(pattern), Note.body.ilike(pattern))
-            query = query.where(filter_)
-            count_query = count_query.where(filter_)
+            terms = q.split()
+            for term in terms:
+                escaped_term = term.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
+                pattern = f"%{escaped_term}%"
+                term_filter = or_(Note.title.ilike(pattern), Note.body.ilike(pattern))
+                query = query.where(term_filter)
+                count_query = count_query.where(term_filter)
 
         if tags:
             for i, tag in enumerate(tags):