feat(contact): full validation, CMS-translated strings, smaller UI

- contact-form-validation.ts: shared client+server validator returning
  {key, params} so messages can be translated via the CMS bundle.
- ContactFormComponent: 3 honeypots, subject field, GDPR consent
  checkbox, character counter, inline per-field errors after submit,
  uses useTranslate() everywhere.
- /api/contact: origin allowlist, multiple honeypot check, client-age
  gate, server-side re-validation, forwards X-Forwarded-For + UA to
  CMS forms plugin with consent timestamp in payload.
- TextInput/Textarea: new size="sm" variant (rounded-sm, shadow-sm,
  h-10, smaller padding/text). Default "md" unchanged.
- translations.ts: 37 new contact_* keys.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/translations.ts

@@ -276,6 +276,44 @@ const TRANSLATION_KEYS = [
   "strommix_trend_flat",
   "strommix_sparkline_aria",         // {{from}}, {{to}}
   "strommix_stale_badge",
+  // Contact form (ContactFormComponent.svelte).
+  "contact_label_name",
+  "contact_placeholder_name",
+  "contact_label_email",
+  "contact_placeholder_email",
+  "contact_label_subject",
+  "contact_placeholder_subject",
+  "contact_label_message",
+  "contact_placeholder_message",
+  "contact_message_remaining",            // {{n}}
+  "contact_message_overflow",             // {{n}}
+  "contact_label_consent",
+  "contact_privacy_note",
+  "contact_submit",
+  "contact_submitting",
+  "contact_success_title",
+  "contact_success_body",
+  "contact_fix_errors",
+  "contact_server_error_generic",
+  "contact_server_error_network",
+  "contact_server_error_blocked",
+  "contact_server_error_throttle",
+  "contact_server_error_validation",
+  // Per-field validation errors (params: n).
+  "contact_error_name_min",               // {{n}}
+  "contact_error_name_max",               // {{n}}
+  "contact_error_name_no_links",
+  "contact_error_name_invalid_chars",
+  "contact_error_email_required",
+  "contact_error_email_max",              // {{n}}
+  "contact_error_email_invalid",
+  "contact_error_subject_max",            // {{n}}
+  "contact_error_subject_invalid_chars",
+  "contact_error_message_min",            // {{n}}
+  "contact_error_message_max",            // {{n}}
+  "contact_error_message_too_many_links", // {{n}}
+  "contact_error_message_invalid_chars",
+  "contact_error_consent_required",
 ] as const;
 
 export type TranslationKey = (typeof TRANSLATION_KEYS)[number];