Donut-hover met percentages en werkende update-notificatie

- Donut: naadloze segmenten (donkere spleten weg), hover-tooltip per
  categorie met naam, bedrag en aandeel, middenwaarde schaalt mee
- Update-check via de eigen backend (/api/update-check) i.p.v. direct
  naar de Gitea API, die geen CORS-headers stuurt
- Semver-vergelijking, herhaalde check en release-notes in de melding
- release.ps1 maakt de Gitea-release aan (stap 4)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/pages/EigenVermogenTab.jsx

@@ -539,7 +539,7 @@ export default function EigenVermogenTab() {
             flex: 1, minWidth: 200,
             display: "flex", flexDirection: "column", alignItems: "center",
           }}>
-            <DonutChart segments={catTotals.map((c) => ({ val: c.tot, color: c.color }))} total={totVerdeling} size={200} label="Verdeling" centerVal={fmt(totVerdeling)} />
+            <DonutChart segments={catTotals.map((c) => ({ val: c.tot, color: c.color, naam: c.naam }))} total={totVerdeling} size={200} label="Verdeling" centerVal={fmt(totVerdeling)} />
             <div style={{ display: "flex", flexWrap: "wrap", gap: "6px 14px", marginTop: 12, justifyContent: "center" }}>
               {catTotals.map((c) => (
                 <div key={c.id} style={{ display: "flex", alignItems: "center", gap: 5 }}>

frontend/src/pages/SchuldTab.jsx

@@ -375,7 +375,7 @@ export default function SchuldTab() {
             display: "flex", flexDirection: "column", alignItems: "center",
           }}>
             <DonutChart
-              segments={schuldCats.map((b) => ({ val: b.subtot, color: b.color }))}
+              segments={schuldCats.map((b) => ({ val: b.subtot, color: b.color, naam: b.naam }))}
               total={donutTotal} size={200} label="Totaal schuld" centerVal={fmt(donutTotal)}
             />
             <div style={{ display: "flex", flexWrap: "wrap", gap: "6px 14px", marginTop: 12, justifyContent: "center" }}>

frontend/src/pages/VoortgangTab.jsx

@@ -347,7 +347,7 @@ export default function VoortgangTab() {
 
         {/* Donut */}
         <VCard style={{ background: T.card, border: `1px solid ${T.border}`, borderRadius: 16, display: "flex", flexDirection: "column", alignItems: "center" }}>
-          <DonutChart segments={[{ val: totEV, color: GREEN }, { val: totSchuld, color: RED }]} total={totEV + totSchuld || 1} size={200} label="Netto waarde" centerVal={fmt(totEV - totSchuld)} />
+          <DonutChart segments={[{ val: totEV, color: GREEN, naam: "Eigen Vermogen" }, { val: totSchuld, color: RED, naam: "Schuld" }]} total={totEV + totSchuld || 1} size={200} label="Netto waarde" centerVal={fmt(totEV - totSchuld)} />
           <div style={{ display: "flex", gap: 20, marginTop: 12, justifyContent: "center" }}>
             <div style={{ display: "flex", alignItems: "center", gap: 6 }}>
               <div style={{ width: 10, height: 10, borderRadius: "50%", background: GREEN }} />