fix(tools): make check-tools compatible with bash 3.x

[yuanchen8911]

Summary

tools-check requires bash 4.0+ and doesn't work with bash 3.*.

• Replace declare -A associative array with a case-based get_tool_metadata() function
• Associative arrays require bash 4.0+, but macOS ships with bash 3.2 by default
• Ensures the script works across all environments without requiring contributors to install a newer bash

Test plan

• Verified make tools-check works on macOS with bash 3.2.57

 make tools-check
=== Tool Version Check ===

Tool                 Expected        Installed       Status
----                 --------        ---------       ------
go                   1.25            1.25            ✓
goreleaser           v2              2.13.3          ✓
ko                   v0.18.0         0.18.0          ✓
crane                v0.20.6         0.20.6          ✓
git-cliff            2.12.0          2.12.0          ✓
golangci-lint        v2.6.2          2.5.0           ✓
yamllint             1.35.0          1.35.1          ✓
addlicense           v1.1.1          -               ✗
go-licenses          v1.6.0          -               ✗
grype                v0.107.0        0.107.0         ✓
kubectl              v1.32           v1.32           ✓
kind                 0.31.0          0.31.0          ✓
ctlptl               0.8.43          0.9.0           ⚠
tilt                 0.35.0          0.36.3          ⚠
helm                 v4.1.0          v4.1.0          ✓
docker               -               27.3.1          ✓

Legend: ✓ = installed, ⚠ = version mismatch or warning, ✗ = missing

[github-actions]

Coverage Report ✅

Metric	Value
Coverage	73.3%
Threshold	70%
Status	Pass

Coverage Badge

![Coverage](https://img.shields.io/badge/coverage-73.3%25-green)

No Go source files changed in this PR.