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/api.ts

@@ -130,6 +130,22 @@ export interface CapitalImportResult {
   statements_written: number;
 }
 
+export interface BatchCapitalFileResult {
+  filename: string;
+  as_of_date: string | null;
+  matched: number;
+  statements_written: number;
+  updated: number;
+  skipped: string[];
+  error: string | null;
+}
+
+export interface BatchCapitalImportResult {
+  entity_id: number;
+  files: BatchCapitalFileResult[];
+  total_statements: number;
+}
+
 export interface CapitalAccount {
   id: number;
   entity_id: number;
@@ -440,6 +456,22 @@ export const api = {
       method: "POST",
       body: JSON.stringify(data),
     }),
+
+  // Batch backfill: several historical eNAV files → capital statements per quarter, auto-matched.
+  capitalImportBatch: async (
+    entityId: number,
+    files: File[],
+    password?: string,
+  ): Promise<BatchCapitalImportResult> => {
+    const form = new FormData();
+    form.set("entity_id", String(entityId));
+    if (password) form.set("password", password);
+    for (const f of files) form.append("files", f);
+    const res = await fetch("/api/import/capital-accounts/batch", { method: "POST", body: form });
+    const data = await res.json().catch(() => ({ detail: res.statusText }));
+    if (!res.ok) throw new ApiError(res.status, data.detail || "Batch import failed");
+    return data;
+  },
   getUser: (id: number) => request<UserDetail>(`/api/users/${id}`),
   createUser: (data: {
     name: string;