Add the trailing period to "einfach produktiv." wherever it was missing

The period is part of the brand name (see Footer.tsx's own comment on
the two-tone logo treatment) — fixed every place it was cleanly
appendable (string/heading endings, or before a dash, matching the
existing precedent in VertragspartnerBlock.tsx). Left the handful of
genuinely awkward mid-sentence spots alone (separable-verb endings,
"einfach produktiv-Konto" hyphenated compounds) rather than force a
period that breaks the sentence — flagging those separately.

Also: Über-mich's checklist now uses the same brand checkmark as
/lebensuhr and /7-tage-klarheits-check instead of plain bullets.

app/die-sieben/components/DieSiebenHero.tsx

@@ -32,7 +32,7 @@ export function DieSiebenHero() {
             Die Sieben<span className="text-brand">.</span>
           </p>
           <p className="font-semibold text-h4 text-text-muted" style={{ fontFamily: "var(--font-lora)" }}>
-            Das Monatsritual von einfach produktiv
+            Das Monatsritual von einfach produktiv.
           </p>
         </div>