fix: address code quality issues, validation gaps, and add test coverage

Phase 1 - Code Quality:
- Rename script/script.rs to script/types.rs (module inception fix)
- Apply Clippy lint fixes (is_none_or, is_some_and, char patterns, etc.)
- Implement FromStr for CatalogFile and Category
- Add filtered_targets() and filtered_repos() helpers to Config

Phase 2 - Validation & Error Handling:
- Add validate_repo_identifier() for GitHub shorthand validation
- Fix first-run setup to fail gracefully if no targets configured
- Improve import to collect failures and only save on success
- Add AssetInstallResult for detailed install failure tracking
- Fix lockfile timestamp documentation (Unix epoch, not RFC 3339)
- Add comprehensive RevType heuristics documentation
- Add checkout warning when local modifications will be discarded

Phase 3 - Test Coverage:
- Add tempfile, assert_cmd, predicates dev dependencies
- Add security tests (symlink boundaries, copy mode)
- Add git operations tests (init, head_commit, RevType parsing)
- Add lockfile tests (roundtrip, lock/get operations)
- Add CLI integration tests (help, validation, duplicates)
- Add config validation tests for new helper methods

All 48 tests pass, clippy clean, release build verified.

tests/cli_integration.rs

@@ -0,0 +1,199 @@
+//! CLI integration tests for empeve
+//!
+//! These tests exercise the binary's command-line interface to ensure
+//! proper user-facing behavior.
+
+use assert_cmd::Command;
+use predicates::prelude::*;
+use tempfile::TempDir;
+
+/// Get a command instance for empeve
+#[allow(deprecated)]
+fn empeve() -> Command {
+    Command::cargo_bin("empeve").unwrap()
+}
+
+#[test]
+fn test_cli_help() {
+    empeve()
+        .arg("--help")
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("Plugin manager for mpv"));
+}
+
+#[test]
+fn test_cli_version() {
+    empeve()
+        .arg("--version")
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("empeve"));
+}
+
+#[test]
+fn test_cli_help_add() {
+    empeve()
+        .args(["add", "--help"])
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("Add a repository"));
+}
+
+#[test]
+fn test_cli_help_install() {
+    empeve()
+        .args(["install", "--help"])
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("Install all configured repositories"));
+}
+
+#[test]
+fn test_cli_help_update() {
+    empeve()
+        .args(["update", "--help"])
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("Update all repositories"));
+}
+
+/// Test that the add command rejects invalid repo formats
+#[test]
+fn test_cli_add_invalid_repo_format() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create minimal config
+    let config_path = config_dir.join("config.toml");
+    std::fs::write(&config_path, "[settings]\n").unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .args(["add", "invalid_repo_no_slash"])
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains("invalid repository format"));
+}
+
+/// Test that the add command accepts valid GitHub shorthand
+#[test]
+fn test_cli_add_valid_repo_format() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create minimal config
+    let config_path = config_dir.join("config.toml");
+    std::fs::write(&config_path, "[settings]\n").unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .args(["add", "user/repo"])
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("Added"));
+
+    // Verify config was updated
+    let config_content = std::fs::read_to_string(&config_path).unwrap();
+    assert!(config_content.contains("user/repo"));
+}
+
+/// Test that adding a duplicate repo fails
+#[test]
+fn test_cli_add_duplicate_fails() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create config with existing repo
+    let config_path = config_dir.join("config.toml");
+    std::fs::write(
+        &config_path,
+        r#"[settings]
+
+[[repos]]
+repo = "existing/repo"
+"#,
+    )
+    .unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .args(["add", "existing/repo"])
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains("already exists"));
+}
+
+/// Test that removing a non-existent repo fails
+#[test]
+fn test_cli_remove_nonexistent_fails() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create empty config
+    let config_path = config_dir.join("config.toml");
+    std::fs::write(&config_path, "[settings]\n").unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .args(["remove", "nonexistent/repo"])
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains("not found"));
+}
+
+/// Test status command with empty config
+#[test]
+fn test_cli_status_empty_config() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create empty config
+    let config_path = config_dir.join("config.toml");
+    std::fs::write(&config_path, "[settings]\n").unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .arg("status")
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("No repositories"));
+}
+
+/// Test that --target flag is recognized
+#[test]
+fn test_cli_target_flag() {
+    let temp = TempDir::new().unwrap();
+    let config_dir = temp.path().join(".config").join("empeve");
+    std::fs::create_dir_all(&config_dir).unwrap();
+
+    // Create config with target
+    let config_path = config_dir.join("config.toml");
+    let mpv_path = temp.path().join("mpv");
+    std::fs::create_dir_all(&mpv_path).unwrap();
+
+    std::fs::write(
+        &config_path,
+        format!(
+            r#"[settings]
+
+[[targets]]
+name = "mpv"
+path = "{}"
+"#,
+            mpv_path.display()
+        ),
+    )
+    .unwrap();
+
+    empeve()
+        .env("XDG_CONFIG_HOME", temp.path().join(".config"))
+        .args(["--target", "mpv", "list"])
+        .assert()
+        .success();
+}