refactor: deduplicate utility helpers across the codebase (#23338)

Audited exported helpers in `coderd/util/*`, `testutil`, `cryptorand`,
and friends, then replaced duplicated implementations with canonical
versions.

- **fix: `maps.SortedKeys` generic signature** — value type was
hardcoded to `any`, making it impossible to actually call. Added second
type parameter `V any`. Added table-driven tests with `cmp.Diff`.
- **refactor: replace ad-hoc ptr helpers with `ptr.Ref`** — removed
`int64Ptr`, `stringPtr`, `boolPtr`, `i64ptr`, `strPtr`, `PtrInt32`
across 6 files.
- **refactor: replace local `sortedKeys`/`sortKeys` with
`maps.SortedKeys`** — now that the signature is fixed, scripts can use
it.
- **refactor: replace hand-rolled `capitalize` with
`strings.Capitalize`** — the typegen version was also not UTF-8 safe.

> 🤖 This PR was created with the help of Coder Agents, and was reviewed
by my human. 🧑‍💻

coderd/util/maps/maps.go

@@ -31,7 +31,7 @@ func Subset[T, U comparable](a, b map[T]U) bool {
 }
 
 // SortedKeys returns the keys of m in sorted order.
-func SortedKeys[T constraints.Ordered](m map[T]any) (keys []T) {
+func SortedKeys[K constraints.Ordered, V any](m map[K]V) (keys []K) {
 	for k := range m {
 		keys = append(keys, k)
 	}

coderd/util/maps/maps_test.go

@@ -4,9 +4,53 @@ import (
 	"strconv"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
+
 	"github.com/coder/coder/v2/coderd/util/maps"
 )
 
+func TestSortedKeys(t *testing.T) {
+	t.Parallel()
+
+	for idx, tc := range []struct {
+		name     string
+		input    map[string]int
+		expected []string
+	}{
+		{
+			name: "SortsAlphabetically",
+			input: map[string]int{
+				"banana": 1,
+				"apple":  2,
+				"cherry": 3,
+			},
+			expected: []string{"apple", "banana", "cherry"},
+		},
+		{
+			name: "AlreadySorted",
+			input: map[string]int{
+				"alpha": 1,
+				"mango": 2,
+				"zebra": 3,
+			},
+			expected: []string{"alpha", "mango", "zebra"},
+		},
+		{
+			name:     "EmptyMap",
+			input:    map[string]int{},
+			expected: nil,
+		},
+	} {
+		t.Run("#"+strconv.Itoa(idx)+"_"+tc.name, func(t *testing.T) {
+			t.Parallel()
+			got := maps.SortedKeys(tc.input)
+			if diff := cmp.Diff(tc.expected, got); diff != "" {
+				t.Fatalf("unexpected result (-want +got):\n%s", diff)
+			}
+		})
+	}
+}
+
 func TestSubset(t *testing.T) {
 	t.Parallel()