lib/shell: add formatShellArrayContent function for intelligent width optimization

Add shared utility function that formats shell arrays with smart width optimization.
Packs multiple items per line based on available width (~78 chars per line) while
maintaining readability. Includes helper functions wrapLines and formatMultiLine.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

modules/lib/shell.nix

@@ -41,6 +41,59 @@ rec {
   # statement for each set entry.
   exportAll = vars: lib.concatStringsSep "\n" (lib.mapAttrsToList export vars);
 
+  # Wrap a list of strings to a given line width.
+  # Packs as many items as possible per line without exceeding maxWidth.
+  # Returns a list of strings, each representing a line.
+  #
+  # Example: wrapLines ["item1" "item2" "very-long-item" "item3"] 20
+  #   => ["item1 item2" "very-long-item" "item3"]
+  wrapLines =
+    items: maxWidth:
+    let
+      step =
+        acc: item:
+        let
+          potentialLine = if acc.currentLine == "" then item else "${acc.currentLine} ${item}";
+        in
+        if lib.stringLength potentialLine <= maxWidth then
+          acc // { currentLine = potentialLine; }
+        else
+          acc
+          // {
+            finishedLines = acc.finishedLines ++ [ acc.currentLine ];
+            currentLine = item;
+          };
+      foldResult = lib.foldl' step {
+        finishedLines = [ ];
+        currentLine = "";
+      } items;
+    in
+    foldResult.finishedLines ++ lib.optional (foldResult.currentLine != "") foldResult.currentLine;
+
+  # Formats a list of items for shell array content with intelligent width optimization.
+  # IMPORTANT: This formats the CONTENTS of an array (what goes inside parentheses),
+  # not a complete array definition. Use lib.hm.zsh.define for complete definitions.
+  #
+  # Uses lib.escapeShellArg for robust shell escaping (handles spaces, quotes, special chars).
+  # Packs multiple items per line to optimize terminal width (~78 chars per line).
+  # Short arrays (≤3 items, ≤80 chars total) use single-line format.
+  #
+  # Example outputs:
+  #   Empty:       ""
+  #   Simple:      item1 item2 item3
+  #   With spaces: 'item one' 'item two' 'item three'
+  #   Long arrays: \n  item1 item2 item3\n  item4 item5\n
+  #
+  # Built from composable helpers: wrapLines, formatMultiLine
+  formatShellArrayContent =
+    items:
+    let
+      quotedItems = lib.map lib.escapeShellArg items;
+      formatMultiLine = lines: "\n  ${lib.concatStringsSep "\n  " lines}\n";
+      wrapped = wrapLines quotedItems 78;
+    in
+    formatMultiLine wrapped;
+
   mkBashIntegrationOption = mkShellIntegrationOption "Bash";
   mkFishIntegrationOption = mkShellIntegrationOption "Fish";
   mkIonIntegrationOption = mkShellIntegrationOption "Ion";