Bump the bundled Terraform binary from 1.16.2 to 1.16.6 (latest stable,
[released
2026-10-14](https://github.com/hashicorp/terraform/releases/tag/v1.16.6)),
following the same file set as #29331:
- `provisioner/terraform/install.go`: `TerraformVersion`
(`maxTerraformVersion` stays at 1.16.9 since this is a patch bump)
- `install.sh`, `scripts/Dockerfile.base`
- `mise.toml`, `mise.lock` (checksums from HashiCorp's
`terraform_1.16.6_SHA256SUMS`)
- `flake.nix` (fetchurl SRI hashes derived from the same SHA256SUMS)
- `docs/install/prepare/airgap.md`: the example Dockerfile `ARG
TERRAFORM_VERSION` had drifted back to 1.11.0 after the docs move;
updated to 1.16.6
Verified locally with `go test ./provisioner/terraform/ -run
'TestInstall|Version'`.
Opened by Superblink on behalf of @droopy4096.
_Updated from 1.16.5 to 1.16.6 (adds an HTTP/2 resource-exhaustion fix).
Branch name still says 1.16.5. Fixture fingerprint (`generation.sha1`)
regenerated; `go test ./provisioner/terraform/ -run
'TestInstall|Version|Golden'` passes._
---------
Co-authored-by: coder[bot] <137810501+coder[bot]@users.noreply.github.com>
Co-authored-by: Dmitry Makovey <dmakovey@yahoo.com>
