ui: aggregated read on top, hide stale rows, wire /log tone toggle; prompts v8

- dashboard grid: explicit "header" area as the first row so the
    aggregated read panel renders at the top instead of being
    auto-placed after the named areas.
  - indicators: hide rows flagged stale (older than the group's
    freshness threshold). Server still computes stale_symbols;
    rendering can be re-enabled by removing the
    `{% if not is_stale %}` wrapper in indicators.html.
  - /log: add tone-changed to #log-content's hx-trigger and include
    it in cassandraSetTone's selector list — toggling Novice /
    Intermediate on the Log page was previously a no-op.
  - prompts: bump PROMPT_VERSION 7→8. Strengthen the rational-vs-
    irrational framing in the strategic-log system prompt from
    aspirational to mandatory ("a paragraph without both lenses must
    be rewritten"). Require the same lens in the per-group summary,
    cross-asset aggregate, and portfolio commentary overrides.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/static/css/cassandra.css

@@ -140,8 +140,9 @@ a:hover { text-decoration: underline; }
   padding: 14px;
   display: grid;
   grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
-  grid-template-rows: auto auto auto;
+  grid-template-rows: auto auto auto auto;
   grid-template-areas:
+    "header     header"
     "indicators log"
     "portfolio  log"
     "news       news";
@@ -150,10 +151,11 @@ a:hover { text-decoration: underline; }
 @media (max-width: 1100px) {
   .app-main {
     grid-template-columns: 1fr;
-    grid-template-areas: "indicators" "portfolio" "log" "news";
+    grid-template-areas: "header" "indicators" "portfolio" "log" "news";
   }
 }
 
+#dash-header-container { grid-area: header; }
 #indicators-panel { grid-area: indicators; }
 #portfolio-panel  { grid-area: portfolio; }
 #log-panel        {