feat(scripts): add generator for template builder module catalog (#26193)

> [!NOTE]
> This PR was authored by Coder Agents on behalf of @jeremyruppel.

Adds `scripts/templatebuildermodulegen/`, a Go tool that fetches module metadata from the Coder registry HTTP API and generates the `module.json` manifests and `.tf.tmpl` files used by the template builder catalog.

The generator calls `GET /api/modules/{id}` for per-module metadata (display name, description, icon, tags, variables) and the Terraform protocol versions endpoint for semver resolution. No git clone or HCL parsing required.

Split into four files:
- `main.go`: orchestration, module config map, CLI flags
- `types.go`: output types (`ModuleManifest`, `ModuleVariable`) and API response types
- `fetch.go`: HTTP fetching, version resolution, variable conversion, icon normalization
- `write.go`: JSON writer, `.tf.tmpl` Go template and writer

scripts/templatebuildermodulegen/write.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"text/template"
+)
+
+func writeModuleJSON(path string, m ModuleManifest) error {
+	data, err := json.MarshalIndent(m, "", "  ")
+	if err != nil {
+		return err
+	}
+	data = append(data, '\n')
+	return os.WriteFile(path, data, 0o600)
+}
+
+var tfTmplTemplate = template.Must(template.New("tf.tmpl").Funcs(template.FuncMap{
+	"hclValue": func(v ModuleVariable) string {
+		if v.Sensitive {
+			return "var." + v.Name
+		}
+		return "{{ .Variables." + v.Name + " }}"
+	},
+}).Parse(`{{- range .SensitiveVars }}
+variable "{{ .Name }}" {
+  description = "{{ .Description }}"
+  type        = {{ .Type }}
+  sensitive   = true
+}
+{{ end -}}
+module "{{ .ID }}" {
+  count    = data.coder_workspace.me.start_count
+  source   = "{{"{{"}} .RegistryBase {{"}}"}}/coder/{{ .ID }}/coder"
+  version  = "{{"{{"}} .PinnedVersion {{"}}"}}"
+  agent_id = coder_agent.{{"{{"}} .AgentResourceName {{"}}"}}.id
+{{- range .NonComputedVars }}
+{{- if .Sensitive }}
+  {{ .Name }} = var.{{ .Name }}
+{{- else }}
+  {{ .Name }} = {{"{{"}} .Variables.{{ .Name }} {{"}}"}}
+{{- end }}
+{{- end }}
+}
+`))
+
+type tfTmplData struct {
+	ID              string
+	SensitiveVars   []ModuleVariable
+	NonComputedVars []ModuleVariable
+}
+
+func writeTFTmpl(path string, m ModuleManifest) error {
+	var sensitiveVars []ModuleVariable
+	var nonComputedVars []ModuleVariable
+	for _, v := range m.Variables {
+		if v.Computed {
+			continue
+		}
+		nonComputedVars = append(nonComputedVars, v)
+		if v.Sensitive {
+			sensitiveVars = append(sensitiveVars, v)
+		}
+	}
+
+	data := tfTmplData{
+		ID:              m.ID,
+		SensitiveVars:   sensitiveVars,
+		NonComputedVars: nonComputedVars,
+	}
+
+	f, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	err = tfTmplTemplate.Execute(f, data)
+	if closeErr := f.Close(); err == nil {
+		err = closeErr
+	}
+	return err
+}