feat(blocks): SectionGrid/InfoCard/ContactForm + Konsolidierung (Tier 1)

Neue Komponenten: SectionGrid, InfoCard (tone/compact), ArrowLink, ContactFormBlock,
SectionGridBlock. CMS-Blöcke section_grid + contact_form (info_card-Collection).
OrganisationsBlock: presentation "grid" (SectionGrid + InfoCard-Tiles).
Kontaktformular-Submit: size md + Send-Icon.

Konsolidierung Tier 1:
- .card-surface + Card-Atom → rounded-lg, .chip → rounded-full, Input-Atome → rounded-md
- tote .btn-*-Klassen aus app.css entfernt (Atom nutzt --color-btn-*-Tokens)
- hardcoded Hex → stein-Tokens (InfoCard, ContactFormBlock)
- redundante rounded-sm auf card-surface-Nutzern entfernt

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/block-types.ts

@@ -370,7 +370,7 @@ export interface OrganisationsBlockData {
   action?: string | { url?: string; linkName?: string; newTab?: boolean };
   description?: string;
   /** default = Karten-Grid; compact = engere Karten, Logo links; carousel = horizontaler Slider (3 Desktop / 2 Mobile) */
-  presentation?: "default" | "compact" | "carousel";
+  presentation?: "default" | "compact" | "carousel" | "grid";
   addOrganisationTitle?: string;
   addOrganisationMarkdown?: string;
   /** Referenz auf link-Collection (aufgelöst: url, linkName, newTab) */
@@ -588,6 +588,8 @@ export interface InfoCardData {
   linkLabel?: string;
   linkHref?: string;
   external?: boolean;
+  /** Farbton der Kachel: default (weiß) oder green (grün getönt). */
+  tone?: "default" | "green";
 }
 
 /** Sektions-Grid (_type: "section_grid"): SectionHeader + info_card-Kacheln. */
@@ -607,3 +609,18 @@ export interface SectionGridBlockData {
   cards?: (string | InfoCardData)[];
   layout?: BlockLayout;
 }
+
+/** Zweispaltiger Formular-Block (_type: "contact_form"): Form links, Aside rechts. */
+export interface ContactFormBlockData {
+  _type?: "contact_form";
+  _slug?: string;
+  headline?: string;
+  kicker?: string;
+  number?: string;
+  action?: string | { url?: string; linkName?: string; newTab?: boolean };
+  form?: "form-contact" | "form-mitmachen" | "form-newsletter" | "form-newsletter-inline";
+  asideTitle?: string;
+  asideText?: string;
+  asideCards?: (string | InfoCardData)[];
+  layout?: BlockLayout;
+}