fix(chart): keep zero-year chara and ephemeris dates apart

A zero-year Chara period is shown as 0 years instead of failing the whole chart. Switching ephemeris dates drops the previous day immediately and can be retried. Missing birth data links to chart settings.

frontend/src/components/chart-page/chart-dasha-tab.tsx

@@ -1,6 +1,6 @@
 import { chartLayerFailureCopy } from "@/lib/chart-view-failure";
 import type { ChartViewFailureStatus, ChartViewOk } from "@/lib/chart-view-contract";
-import { CHART_VIEW_COPY } from "@/lib/chart-view-labels";
+import { CHARA_ZERO_YEAR_LABEL, CHARA_ZERO_YEAR_NOTE, CHART_VIEW_COPY } from "@/lib/chart-view-labels";
 
 function Track({
   title,
@@ -28,9 +28,11 @@ function Track({
           >
             <p>
               <strong>{period.label}</strong>
-              <span>{period.start} – {period.end}</span>
+              <span>{period.zeroYear ? CHARA_ZERO_YEAR_LABEL : `${period.start} – ${period.end}`}</span>
             </p>
-            {period.antardashas.length > 0 ? (
+            {period.zeroYear ? (
+              <p className="chart-page-note">{CHARA_ZERO_YEAR_NOTE}</p>
+            ) : period.antardashas.length > 0 ? (
               <ul>
                 {period.antardashas.map((antar) => (
                   <li key={`${antar.lord}-${antar.start}`} className={antar.current ? "is-current" : undefined}>

frontend/src/components/chart-page/chart-page-view.tsx

@@ -12,6 +12,7 @@ import {
 } from "@/lib/chart-view-contract";
 import type { ChartViewLayer } from "@/lib/chart-view-engine";
 import { CHART_VIEW_COPY } from "@/lib/chart-view-labels";
+import { CHART_SETTINGS_HREF } from "@/lib/settings-url";
 import { chartLayerFailureCopy } from "@/lib/chart-view-failure";
 import { ChartPageSkeleton } from "./chart-page-skeleton";
 import { ChartBasicsTab } from "./chart-basics-tab";
@@ -36,6 +37,19 @@ function WaitingNote({ copy }: { copy: string }) {
   return <p className="chart-page-note">{copy}</p>;
 }
 
+const PROFILE_ENTRY_REASONS = new Set([
+  "profile_incomplete",
+  "profile_query_error",
+  "adopted_calculation_incomplete",
+  "timezone_resolver_failure",
+]);
+
+function showsProfileEntry(view: ChartViewResponse): boolean {
+  if (view.status === "ok") return false;
+  if (view.status === "birth_profile_incomplete") return true;
+  return view.reason != null && PROFILE_ENTRY_REASONS.has(view.reason);
+}
+
 export function ChartPageView({
   view,
   pendingLayers,
@@ -75,7 +89,11 @@ export function ChartPageView({
     >
       {view != null && view.status !== "ok" ? (
         <section className="chart-page-message">
+          {view.status === "birth_profile_incomplete" ? <h2>{CHART_VIEW_COPY.profileEntryTitle}</h2> : null}
           <p>{view.message}</p>
+          {showsProfileEntry(view) ? (
+            <a className="button-primary" href={CHART_SETTINGS_HREF}>{CHART_VIEW_COPY.profileEntryAction}</a>
+          ) : null}
         </section>
       ) : (
         <div className="chart-page-body">