0.2.25: batch historical eNAV backfill + collapsible investor chart

Add POST /api/import/capital-accounts/batch: upload several of a fund's
eNAV workbooks at once; each file's ALLOC SI roster is auto-matched to
existing members (by fund-admin investor ID, else name/username) and their
capital statement is saved at that file's own as-of date, building
trend-lines without replacing the latest figures. Members not already in
the portal are skipped and reported per file (never created). Capital
statements only -- holdings/NAV are untouched. One bad file (wrong
password, no ALLOC SI, unreadable date) is reported per-file and does not
abort the rest.

Import page gains a "Backfill historical capital" batch section (fund
picker, multi-file .xlsx input, shared password, per-file results table).

Investor portal "Capital over time" chart is now collapsed by default and
expands per fund (first login opens clean); applies to InvestorHome and
the admin Investor View via the shared component.

Tests: backend/tests/test_capital_batch.py (2). Full suite 17 passed;
frontend tsc clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/portal/InvestorPortalView.tsx

@@ -1,4 +1,4 @@
-import { useMemo } from "react";
+import { useMemo, useState } from "react";
 import { api, type CapitalAccount, type Entity, type PortalDocument } from "../api";
 import { categoryLabel, formatDate, formatMoneyExact } from "../format";
 import CapitalChart, { type CapitalPoint } from "../components/CapitalChart";
@@ -125,6 +125,8 @@ function CapitalBlock({
     paidIn: a.contributions_cents,
     distributions: a.distributions_cents,
   }));
+  // Collapsed by default so the portal opens clean; the investor expands the trend per fund.
+  const [showChart, setShowChart] = useState(false);
 
   return (
     <div className={divider ? "mt-6 pt-5 border-t border-gray-100" : "mt-3"}>
@@ -150,7 +152,20 @@ function CapitalBlock({
 
       {history.length > 1 && (
         <div className="mt-5">
-          <h3 className="text-xs font-medium text-gray-500 uppercase mb-2">Capital over time</h3>
+          <button
+            type="button"
+            onClick={() => setShowChart((v) => !v)}
+            aria-expanded={showChart}
+            className="flex items-center gap-1.5 text-xs font-medium text-gray-500 uppercase hover:text-gray-700"
+          >
+            <span className={`transition-transform ${showChart ? "rotate-90" : ""}`}>▸</span>
+            Capital over time
+            <span className="normal-case font-normal text-gray-400">
+              ({history.length} quarters{showChart ? "" : " — show"})
+            </span>
+          </button>
+          {showChart && (
+          <div className="mt-3">
           <CapitalChart points={chartPoints} />
           <table className="w-full text-sm mt-4">
             <thead className="text-gray-400 text-left">
@@ -172,6 +187,8 @@ function CapitalBlock({
               ))}
             </tbody>
           </table>
+          </div>
+          )}
         </div>
       )}
     </div>