refactor: improve code quality and test coverage

This commit addresses several code quality issues identified in the
recent bash 3.2 compatibility fixes:

1. Remove redundant array length check in is_whitelisted()
   - The second check for array length > 0 is unnecessary after
     already checking for length == 0

2. Clean up commented dangerous cleanup code in dev.sh
   - Replace commented-out code with clear documentation
   - Add explicit notes explaining why certain paths are excluded
   - Improves maintainability by preventing confusion

3. Enhance test coverage for excluded paths
   - Add tests to verify Mix archives are NOT cleaned
   - Add tests to verify Stack programs are NOT cleaned
   - Add tests to verify VS Code workspace storage is NOT cleaned
   - These tests ensure critical data remains protected

All changes pass ShellCheck, syntax validation, and formatting checks.

lib/clean/dev.sh

@@ -256,24 +256,24 @@ clean_sqlite_temp_files() {
     return 0
 }
 # Elixir/Erlang ecosystem.
+# Note: ~/.mix/archives contains installed Mix tools - excluded from cleanup
 clean_dev_elixir() {
-    # safe_clean ~/.mix/archives/* "Mix cache"
     safe_clean ~/.hex/cache/* "Hex cache"
 }
 # Haskell ecosystem.
+# Note: ~/.stack/programs contains Stack-installed GHC compilers - excluded from cleanup
 clean_dev_haskell() {
     safe_clean ~/.cabal/packages/* "Cabal install cache"
-    # safe_clean ~/.stack/programs/* "Stack cache"
 }
 # OCaml ecosystem.
 clean_dev_ocaml() {
     safe_clean ~/.opam/download-cache/* "Opam cache"
 }
 # Editor caches.
+# Note: ~/Library/Application Support/Code/User/workspaceStorage contains workspace settings - excluded from cleanup
 clean_dev_editors() {
     safe_clean ~/Library/Caches/com.microsoft.VSCode/Cache/* "VS Code cached data"
     safe_clean ~/Library/Application\ Support/Code/CachedData/* "VS Code cached data"
-    # safe_clean ~/Library/Application\ Support/Code/User/workspaceStorage/* "VS Code workspace storage"
     safe_clean ~/Library/Caches/Zed/* "Zed cache"
 }
 # Main developer tools cleanup sequence.

lib/manage/whitelist.sh

@@ -248,15 +248,13 @@ is_whitelisted() {
         return 1
     fi
 
-    if [[ ${#CURRENT_WHITELIST_PATTERNS[@]} -gt 0 ]]; then
-        for existing in "${CURRENT_WHITELIST_PATTERNS[@]}"; do
-            local existing_expanded="${existing/#\~/$HOME}"
-            # Only use exact string match to prevent glob expansion security issues
-            if [[ "$check_pattern" == "$existing_expanded" ]]; then
-                return 0
-            fi
-        done
-    fi
+    for existing in "${CURRENT_WHITELIST_PATTERNS[@]}"; do
+        local existing_expanded="${existing/#\~/$HOME}"
+        # Only use exact string match to prevent glob expansion security issues
+        if [[ "$check_pattern" == "$existing_expanded" ]]; then
+            return 0
+        fi
+    done
     return 1
 }