chore(deps): update ubuntu docker tag to v26 (#1251)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| ubuntu | stage | major | `24.04` → `26.04` |

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Dockerfile

@@ -1,7 +1,7 @@
 # Multi-stage Dockerfile for chromad Go application using Hermit-managed tools
 
 # Build stage
-FROM ubuntu:24.04 AS builder
+FROM ubuntu:26.04 AS builder
 
 # Install system dependencies
 RUN apt-get update && apt-get install -y \