refactor: Cleanup git state - commit all staged changes

Major refactoring cleanup:
- Add new controller architecture (class-controller-*.php)
- Add new settings-v2 UI (views/settings-v2/)
- Add new CSS architecture (agentic-sidebar.css, tokens)
- Add esbuild build pipeline (scripts/build.js, package.json)
- Add composer dependencies (vendor/)
- Add frontend src directory (assets/js/src/index.jsx)
- Add documentation files
- Remove old/obsolete files (class-settings.php, old CSS)

This commits all pending changes from previous refactoring efforts.

vendor/bin/plantuml

@@ -0,0 +1,37 @@
+#!/usr/bin/env sh
+
+# Support bash to support `source` with fallback on $0 if this does not run with bash
+# https://stackoverflow.com/a/35006505/6512
+selfArg="$BASH_SOURCE"
+if [ -z "$selfArg" ]; then
+    selfArg="$0"
+fi
+
+self=$(realpath "$selfArg" 2> /dev/null)
+if [ -z "$self" ]; then
+    self="$selfArg"
+fi
+
+dir=$(cd "${self%[/\\]*}" > /dev/null; cd '../jawira/plantuml/bin' && pwd)
+
+if [ -d /proc/cygdrive ]; then
+    case $(which php) in
+        $(readlink -n /proc/cygdrive)/*)
+            # We are in Cygwin using Windows php, so the path must be translated
+            dir=$(cygpath -m "$dir");
+            ;;
+    esac
+fi
+
+export COMPOSER_RUNTIME_BIN_DIR="$(cd "${self%[/\\]*}" > /dev/null; pwd)"
+
+# If bash is sourcing this file, we have to source the target as well
+bashSource="$BASH_SOURCE"
+if [ -n "$bashSource" ]; then
+    if [ "$bashSource" != "$0" ]; then
+        source "${dir}/plantuml" "$@"
+        return
+    fi
+fi
+
+exec "${dir}/plantuml" "$@"