chore(deps): update golang docker tag to v1.26 (#450)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| golang | final | minor | `1.25-alpine` → `1.26-alpine` |

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Dockerfile

@@ -17,7 +17,7 @@ COPY internal/web/ ./internal/web/
 
 RUN pnpm build:assets
 
-FROM golang:1.25-alpine AS backend-builder
+FROM golang:1.26-alpine AS backend-builder
 WORKDIR /build
 
 # Copy dependency files