Update Gold and Silver sponsorship availability (#205)

Sets Gold availability to 0 (sold out) and Silver to 8, updated across
all three locales (en, es, ca).

## Changes

- `tiers.items` in `en.ts`, `es.ts`, `ca.ts`:
  - Gold: `2 avail.` → `0 avail.` / `0 disp.`
  - Silver: `9 avail.` → `8 avail.` / `8 disp.`

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

src/i18n/sponsors/ca.ts

@@ -219,7 +219,7 @@ export const ca = {
         emoji: '⚪',
         iconName: 'silver',
         price: 'Preu 3.000€',
-        limit: '9 disp.',
+        limit: '8 disp.',
         bg: 'rgba(107, 114, 128, 0.1)',
       },
       {
@@ -228,7 +228,7 @@ export const ca = {
         emoji: '🌟',
         iconName: 'gold',
         price: 'Preu 6.000€',
-        limit: '2 disp.',
+        limit: '0 disp.',
         bg: 'rgba(234, 179, 8, 0.1)',
       },
       {

src/i18n/sponsors/en.ts

@@ -223,7 +223,7 @@ export const en = {
         emoji: '⚪',
         iconName: 'silver',
         price: 'Price €3,000',
-        limit: '9 avail.',
+        limit: '8 avail.',
         bg: 'rgba(107, 114, 128, 0.1)',
       },
       {
@@ -232,7 +232,7 @@ export const en = {
         emoji: '🌟',
         iconName: 'gold',
         price: 'Price €6,000',
-        limit: '2 avail.',
+        limit: '0 avail.',
         bg: 'rgba(234, 179, 8, 0.1)',
       },
       {

src/i18n/sponsors/es.ts

@@ -239,7 +239,7 @@ export const es = {
         emoji: '⚪',
         iconName: 'silver',
         price: 'Precio 3.000€',
-        limit: '9 disp.',
+        limit: '8 disp.',
         bg: 'rgba(107, 114, 128, 0.1)',
       },
       {
@@ -248,7 +248,7 @@ export const es = {
         emoji: '🌟',
         iconName: 'gold',
         price: 'Precio 6.000€',
-        limit: '2 disp.',
+        limit: '0 disp.',
         bg: 'rgba(234, 179, 8, 0.1)',
       },
       {