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>

backend/ten31portal/schemas.py

@@ -320,6 +320,24 @@ class CapitalImportCommit(BaseModel):
     investors: list[ImportCommitInvestor]
 
 
+# --- Batch historical capital backfill (one eNAV file per quarter, auto-matched) ---
+
+class BatchCapitalFileResult(BaseModel):
+    filename: str
+    as_of_date: date | None = None
+    matched: int = 0                 # existing members whose statement was written
+    statements_written: int = 0      # created + updated
+    updated: int = 0                 # matched a statement already at this as-of date
+    skipped: list[str] = []          # roster names with no existing member (not created)
+    error: str | None = None         # file-level failure (bad password, no ALLOC SI, etc.)
+
+
+class BatchCapitalImportResult(BaseModel):
+    entity_id: int
+    files: list[BatchCapitalFileResult]
+    total_statements: int
+
+
 # --- Entity stakes (a GP/mgmt entity's interest in the funds it manages) ---
 
 class EntityStakeCreate(BaseModel):