fix(target): make --target flag case insensitive to match Tanka (#56)

Tanka's --target flag performs case-insensitive regex matching on
kind/name, but rtk was using case-sensitive matching. This caused
filters like "configmap/.*" to not match "ConfigMap" resources.

Fix both target filtering code paths (extract_manifests in util.rs
for show/apply/diff/prune, and compile_target_patterns in export.rs
for export) to use RegexBuilder with case_insensitive(true).

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: julienduchesne

cmds/rtk/src/commands/util.rs

@@ -127,7 +127,7 @@ pub fn extract_manifests(
 	if !target_filters.is_empty() {
 		let filters: Vec<regex::Regex> = target_filters
 			.iter()
-			.map(|f| regex::Regex::new(f))
+			.map(|f| regex::RegexBuilder::new(f).case_insensitive(true).build())
 			.collect::<Result<Vec<_>, _>>()
 			.context("invalid target filter regex")?;
 

cmds/rtk/src/export.rs

@@ -317,7 +317,10 @@ fn compile_target_patterns(patterns: &[String]) -> Result<Vec<regex::Regex>> {
 	patterns
 		.iter()
 		.map(|p| {
-			regex::Regex::new(p).map_err(|e| anyhow::anyhow!("Invalid target regex '{}': {}", p, e))
+			regex::RegexBuilder::new(p)
+				.case_insensitive(true)
+				.build()
+				.map_err(|e| anyhow::anyhow!("Invalid target regex '{}': {}", p, e))
 		})
 		.collect()
 }

test_fixtures/golden_envs/target_filter_case_insensitive_env/golden/default/ConfigMap-app-config.golden

@@ -0,0 +1,7 @@
+apiVersion: v1
+data:
+  key: value
+kind: ConfigMap
+metadata:
+  name: app-config
+  namespace: default

test_fixtures/golden_envs/target_filter_case_insensitive_env/golden/manifest.json

@@ -0,0 +1,3 @@
+{
+    "default/ConfigMap-app-config.golden": "main.jsonnet"
+}

test_fixtures/golden_envs/target_filter_case_insensitive_env/jsonnetfile.json

@@ -0,0 +1,5 @@
+{
+  "version": 1,
+  "dependencies": [],
+  "legacyImports": true
+}

test_fixtures/golden_envs/target_filter_case_insensitive_env/main.jsonnet

@@ -0,0 +1,54 @@
+// Test environment for case-insensitive --target flag
+// Tanka's --target is case insensitive, so "configmap/.*" should match "ConfigMap"
+
+local env = {
+  apiVersion: 'tanka.dev/v1alpha1',
+  kind: 'Environment',
+  metadata: {
+    name: 'target-filter-case-insensitive-test',
+  },
+  spec: {
+    apiServer: 'https://localhost:6443',
+    namespace: 'default',
+  },
+  data: {
+    // This should be exported (matches configmap/.* case-insensitively)
+    'app-config': {
+      apiVersion: 'v1',
+      kind: 'ConfigMap',
+      metadata: {
+        name: 'app-config',
+        namespace: 'default',
+      },
+      data: {
+        key: 'value',
+      },
+    },
+    // This should NOT be exported (Deployment doesn't match configmap/.*)
+    'app-deployment': {
+      apiVersion: 'apps/v1',
+      kind: 'Deployment',
+      metadata: {
+        name: 'app',
+        namespace: 'default',
+      },
+      spec: {
+        replicas: 1,
+        selector: {
+          matchLabels: { app: 'app' },
+        },
+        template: {
+          metadata: { labels: { app: 'app' } },
+          spec: {
+            containers: [{
+              name: 'main',
+              image: 'nginx:1.25',
+            }],
+          },
+        },
+      },
+    },
+  },
+};
+
+env

test_fixtures/golden_envs/target_filter_case_insensitive_env/tk-compare.toml

@@ -0,0 +1,2 @@
+[args]
+export = ["--target", "configmap/.*"]