docs: carry the risk-monitor wording through docs, comments and logs

Follows 5ea0785, which renamed the user-visible labels. This finishes the pass
so code, docs and operator output use one vocabulary: README (pipeline list,
route table, FRED row), the methodology doc title, .env.example and config
comments, the snapshot model / event-study / service / test docstrings, the
scheduler section headers and morning-pipeline docstring, the TopBar status
text ("bullish regime" -> "bullish trend"), and the four "Regime monitor:" log
prefixes.

Deliberately NOT changed, because "market regime" is also a standard finance
term and most occurrences are not this job: the backtest caveat "~6 months is
roughly one market regime" in backtest_service, README, BacktestPanel and every
generated reports/*.json; "a regime shift" in TrackRecordPanel; and the
capacity-bracket findings doc. Renaming those would have made the text wrong.

Also unchanged, being persisted or externally linked rather than wording: the
regime_monitor / market_regime job ids, the regime_quadrant_enabled setting key,
the /regime route, METHODOLOGY and the snapshot fields, the service/test module
filenames, and docs/research/regime-monitor-v3.md's path (referenced from commit
messages). The doc now carries a one-line note recording the old name and why
those identifiers still use it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

frontend/src/components/layout/TopBar.tsx

@@ -85,7 +85,7 @@ export default function TopBar() {
       </div>
 
       <div className="ml-auto flex items-center gap-5">
-        {/* Market regime — ambient status; the full picture lives on /regime */}
+        {/* SPY trend — ambient status; the full picture lives on /regime */}
         {regime.data && (
           <NavLink
             to="/regime"
@@ -100,7 +100,7 @@ export default function TopBar() {
           >
             <span className={`inline-block h-1.5 w-1.5 rounded-full ${regimeDot(regime.data.label)}`} />
             <span className="text-[11px] capitalize text-gray-500 transition-colors group-hover:text-gray-300">
-              {regime.data.label} regime
+              {regime.data.label} trend
             </span>
           </NavLink>
         )}