Upgrade Go to 1.26

[chrisreddington]

Summary

Upgrades the module's Go version from 1.25.0 to 1.26.3 (the latest patch as of May 2026).

Changes

• go.mod: bump go directive from 1.25.0 → 1.26.3

Why

• Go 1.26 is the latest stable major release (initial release Feb 2026).
• Keeps the project on a fully-supported Go release line with current security and performance fixes.

CI impact

None required. All workflows already track go.mod:

• build.yml and linter.yml use actions/setup-go with go-version-file: go.mod
• release.yml uses cli/gh-extension-precompile with go_version_file: go.mod

Verification

• go mod tidy — clean, no dependency changes
• go build ./... — passes
• go test ./... — all packages pass
• End-to-end smoke test: generated an STL for a real user/year; output validated (binary STL header well-formed, triangle count matches file size, ASCII preview rendered correctly)

[Copilot]

Pull request overview

Upgrades the module’s Go version in go.mod to target Go 1.26.3 so CI and local builds use the newer Go toolchain line.

Changes:

• Bump the go directive in go.mod from 1.25.0 to 1.26.3.

Show a summary per file

File	Description
go.mod	Updates the Go version directive to Go 1.26.3.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 1