bump to v0.2.0: complete provider implementation with live-tested DNS record types

- DYNU_API_KEY env var fallback in provider config
- dynu_domain resource: add 9 computed attributes (unicode_name, ipv4/ipv6 flags,
  wildcard aliases, allow_zone_transfer, dnssec, created_on, updated_on)
- dynu_dns_records data source: add 6 type-specific fields (priority, weight,
  port, flags, tag, value)
- Fix normalizeRecordContentForState for MX/SRV/NS/PTR (read host field) and CAA
  (read value field) to avoid plan/state inconsistency
- Allow underscore-prefixed DNS labels in hostname validator (RFC 2782 SRV)
- Preserve plan/state hostname across create/update/read to prevent inconsistent
  result errors when API returns full FQDN for node_name-style records
- Update all version references from 0.1.0 to 0.2.0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LFZyrmtKsezBwFWGTWsb2y

internal/provider/provider_test.go

@@ -16,16 +16,23 @@ func TestResolveAPIKey(t *testing.T) {
 	tests := []struct {
 		name   string
 		config types.String
+		envVal string
 		want   string
 	}{
 		{name: "configured", config: types.StringValue("config-key"), want: "config-key"},
 		{name: "null when missing", config: types.StringNull(), want: ""},
 		{name: "trim spaces", config: types.StringValue("  config-key "), want: "config-key"},
 		{name: "unknown when pending", config: types.StringUnknown(), want: ""},
+		{name: "env var fallback when null", config: types.StringNull(), envVal: "env-key", want: "env-key"},
+		{name: "config takes priority over env", config: types.StringValue("config-key"), envVal: "env-key", want: "config-key"},
+		{name: "env var fallback when unknown", config: types.StringUnknown(), envVal: "env-key", want: "env-key"},
 	}
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
+			if tc.envVal != "" {
+				t.Setenv("DYNU_API_KEY", tc.envVal)
+			}
 			if got := resolveAPIKey(tc.config); got != tc.want {
 				t.Fatalf("resolveAPIKey() = %q, want %q", got, tc.want)
 			}