0.2.27-0.2.32: LP portal polish, brand palette, default investor logins

Cumulative checkpoint since 0.2.26:
- 0.2.27/28: entity valuation-history table; investor gain/loss = NAV +
  distributions vs paid-in
- 0.2.29: Reset Fund Partners (endpoint, Partners-tab button, CLI, action)
- 0.2.30: "Current Capital Balance" label, %-only gain/loss
- 0.2.31: Management Entities rename, Carry Vehicle type, chart
  distributions-line gate
- 0.2.32: LP-facing polish pass
  * Ten31 brand palette from the logo (navy/mint); orange retired
  * portfolio summary card across funds; gain labeled "net of paid-in"
  * whole-dollar headline figures; "History · N quarters" toggle
  * documents grouped by year with a "New" badge (users.docs_seen_at)
  * eNAV-created members start on default password with login enabled;
    enable-investor-logins CLI + StartOS action for existing accounts
  * password minimum raised to 8 chars; login help line (Portal@ten31.xyz)

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

backend/ten31portal/routers/auth_router.py

@@ -87,8 +87,8 @@ def change_password(
     """Let the signed-in user set their own password (after confirming the current one)."""
     if not verify_password(body.current_password, user.password_hash):
         raise HTTPException(status_code=400, detail="Current password is incorrect.")
-    if len(body.new_password) < 4:
-        raise HTTPException(status_code=400, detail="New password must be at least 4 characters.")
+    if len(body.new_password) < 8:
+        raise HTTPException(status_code=400, detail="New password must be at least 8 characters.")
     user.password_hash = hash_password(body.new_password)
     session.add(user)
     session.commit()