chore(deps): Upgrade Go to 1.26.0 and update dependencies

[shivasurya]

Summary

• Upgrade Go from 1.25.6 to 1.26.0 (released Feb 10, 2026) across go.mod, go.work, and all CI workflows (build.yml, release.yml)
• Upgrade GitHub Actions: actions/setup-go v5 → v6, codecov/codecov-action v4.0.1 → v5
• Upgrade golangci-lint from v2.5.0 to v2.9.0 (includes Go 1.26 support)
• Bump Go module dependencies:
  • posthog/posthog-go v1.9.1 → v1.10.0 (latest)
  • golang.org/x/term v0.39.0 → v0.40.0
  • golang.org/x/sys v0.40.0 → v0.41.0
• Add mise.toml to .gitignore for local tooling config

Test plan

• All 26 Go test packages pass locally with Go 1.26.0
• Build succeeds with Go 1.26.0
• golangci-lint v2.9.0 reports 0 issues
• Verified all versions from official sources (go.dev/dl, GitHub releases)
• golangci-lint binary authenticity verified (GitHub attestations, commit hash match)
• posthog-go v1.10.0 confirmed as latest available version
• CI build and lint pass on GitHub Actions

🤖 Generated with Claude Code

[safedep]

SafeDep Report Summary

Package Details

Package	Malware	Vulnerability	Risky License	Report
github.com/posthog/posthog-go @ v1.10.0 sast-engine/go.mod				🔗
golang.org/x/sys @ v0.41.0 sast-engine/go.mod				🔗
golang.org/x/term @ v0.40.0 sast-engine/go.mod				🔗

_{This report is generated by SafeDep Github App}

[github-actions]

Code Pathfinder Security Scan

No security issues detected.

Metric	Value
Files Scanned	6
Rules	38

---

_{Powered by Code Pathfinder}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.54%. Comparing base (4955bdd) to head (6b544a4).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #516   +/-   ##
=======================================
  Coverage   82.54%   82.54%           
=======================================
  Files         122      122           
  Lines       14097    14097           
=======================================
  Hits        11636    11636           
  Misses       2016     2016           
  Partials      445      445           

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