add more san version info via cli output

[hchenxa]

Duplicate check

• I searched existing issues and discussions and didn't find a duplicate

Problem

san version
• Print the current san version, build time, Go version, and other basic build info
• Support a --json flag for machine-readable output (useful for scripts)

Proposed solution

Example:

$ san version
san version 1.2.3
build: 2026-07-10
go:    go1.22

$ san version --json
{
  "version": "1.2.3",
  "build_time": "2026-07-10",
  "go_version": "go1.22",
  "commit": "abc1234"
}

Alternatives considered

No response