Fix code quality violations and exclude Manifest from checks

Document application modes (development/debug/production)
Add global file drop handler, order column normalization, SPA hash fix
Serve CDN assets via /_vendor/ URLs instead of merging into bundles
Add production minification with license preservation
Improve JSON formatting for debugging and production optimization
Add CDN asset caching with CSS URL inlining for production builds
Add three-mode system (development, debug, production)
Update Manifest CLAUDE.md to reflect helper class architecture
Refactor Manifest.php into helper classes for better organization
Pre-manifest-refactor checkpoint: Add app_mode documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

node_modules/css-tree/lib/syntax/node/Feature.js

@@ -0,0 +1,103 @@
+import {
+    Ident,
+    Number,
+    Dimension,
+    Function as FunctionToken,
+    LeftParenthesis,
+    RightParenthesis,
+    Colon,
+    Delim
+} from '../../tokenizer/index.js';
+
+const SOLIDUS = 0x002F;  // U+002F SOLIDUS (/)
+
+export const name = 'Feature';
+export const structure = {
+    kind: String,
+    name: String,
+    value: ['Identifier', 'Number', 'Dimension', 'Ratio', 'Function', null]
+};
+
+export function parse(kind) {
+    const start = this.tokenStart;
+    let name;
+    let value = null;
+
+    this.eat(LeftParenthesis);
+    this.skipSC();
+
+    name = this.consume(Ident);
+    this.skipSC();
+
+    if (this.tokenType !== RightParenthesis) {
+        this.eat(Colon);
+        this.skipSC();
+
+        switch (this.tokenType) {
+            case Number:
+                if (this.lookupNonWSType(1) === Delim) {
+                    value = this.Ratio();
+                } else {
+                    value = this.Number();
+                }
+
+                break;
+
+            case Dimension:
+                value = this.Dimension();
+                break;
+
+            case Ident:
+                value = this.Identifier();
+                break;
+
+            case FunctionToken:
+                value = this.parseWithFallback(
+                    () => {
+                        const res = this.Function(this.readSequence, this.scope.Value);
+
+                        this.skipSC();
+
+                        if (this.isDelim(SOLIDUS)) {
+                            this.error();
+                        }
+
+                        return res;
+                    },
+                    () => {
+                        return this.Ratio();
+                    }
+                );
+                break;
+
+            default:
+                this.error('Number, dimension, ratio or identifier is expected');
+        }
+
+        this.skipSC();
+    }
+
+    if (!this.eof) {
+        this.eat(RightParenthesis);
+    }
+
+    return {
+        type: 'Feature',
+        loc: this.getLocation(start, this.tokenStart),
+        kind,
+        name,
+        value
+    };
+}
+
+export function generate(node) {
+    this.token(LeftParenthesis, '(');
+    this.token(Ident, node.name);
+
+    if (node.value !== null) {
+        this.token(Colon, ':');
+        this.node(node.value);
+    }
+
+    this.token(RightParenthesis, ')');
+}