feat(web): implement complete workspace with themes, tabs, sidebar, and mobile

Transform CalcText from a single-document calculator into a full workspace
application with multi-document support, theming, and responsive mobile experience.

- Theme system: 5 presets (Light, Dark, Matrix, Midnight, Warm) + accent colors
- Document model with localStorage persistence and auto-save
- Tab bar with keyboard shortcuts (Ctrl+N/W/Tab/1-9), rename, close
- Sidebar with search, recent, favorites, folders, templates, drag-and-drop
- 5 templates: Budget, Invoice, Unit Converter, Trip Planner, Loan Calculator
- Status bar with cursor position, engine status, dedication to Igor Cassel
- Results panel: type-specific colors, click-to-copy, error hints
- Format toolbar: H, B, I, //, color labels with live preview toggle
- Syntax highlighting using theme CSS variables
- Error hover tooltips
- Mobile: bottom results tray, sidebar drawer, touch targets, safe areas
- Docker multi-stage build (Rust WASM + Vite + Nginx)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

calcpad-macos/Sources/CalcPad/Views/EditorTextView.swift

@@ -1,6 +1,52 @@
 import AppKit
 import SwiftUI
 
+// MARK: - StripedTextView
+
+/// NSTextView subclass that draws alternating row background stripes.
+/// Used by both the editor and answer column to provide zebra-striping
+/// that visually connects lines across panes.
+final class StripedTextView: NSTextView {
+    /// Subtle stripe color for odd-numbered lines.
+    static let stripeColor = NSColor.secondaryLabelColor.withAlphaComponent(0.04)
+
+    override func drawBackground(in rect: NSRect) {
+        super.drawBackground(in: rect)
+
+        guard let layoutManager = layoutManager,
+              let textContainer = textContainer else { return }
+
+        let stripeColor = Self.stripeColor
+
+        // We need the absolute line index (not just visible lines) so that
+        // the stripe pattern stays consistent when scrolling and matches
+        // the answer column. Walk all line fragments from the start of the
+        // document, but only fill those that intersect the dirty rect.
+        let fullGlyphRange = layoutManager.glyphRange(for: textContainer)
+        var lineIndex = 0
+
+        layoutManager.enumerateLineFragments(forGlyphRange: fullGlyphRange) {
+            fragmentRect, _, _, _, _ in
+
+            if lineIndex % 2 == 1 {
+                var stripeRect = fragmentRect
+                stripeRect.origin.x = 0
+                stripeRect.size.width = self.bounds.width
+                stripeRect.origin.y += self.textContainerInset.height
+
+                // Only draw if the stripe intersects the dirty rect
+                if stripeRect.intersects(rect) {
+                    stripeColor.setFill()
+                    NSBezierPath.fill(stripeRect)
+                }
+            }
+            lineIndex += 1
+        }
+    }
+}
+
+// MARK: - EditorTextView
+
 /// A SwiftUI wrapper around NSTextView for the editor pane.
 /// Uses NSViewRepresentable to bridge AppKit's NSTextView into SwiftUI,
 /// providing line-level control, scroll position access, and performance
@@ -9,6 +55,7 @@ struct EditorTextView: NSViewRepresentable {
     @Binding var text: String
     @Binding var scrollOffset: CGFloat
     var font: NSFont
+    var alignment: NSTextAlignment = .left
 
     func makeCoordinator() -> Coordinator {
         Coordinator(self)
@@ -22,7 +69,7 @@ struct EditorTextView: NSViewRepresentable {
         scrollView.borderType = .noBorder
         scrollView.drawsBackground = false
 
-        let textView = NSTextView()
+        let textView = StripedTextView()
         textView.isEditable = true
         textView.isSelectable = true
         textView.allowsUndo = true
@@ -33,11 +80,11 @@ struct EditorTextView: NSViewRepresentable {
         textView.isAutomaticTextReplacementEnabled = false
         textView.isAutomaticSpellingCorrectionEnabled = false
 
-        // Disable line wrapping — horizontal scroll instead
-        textView.isHorizontallyResizable = true
-        textView.textContainer?.widthTracksTextView = false
+        // Enable line wrapping — tracks text view width
+        textView.isHorizontallyResizable = false
+        textView.textContainer?.widthTracksTextView = true
         textView.textContainer?.containerSize = NSSize(
-            width: CGFloat.greatestFiniteMagnitude,
+            width: 0,
             height: CGFloat.greatestFiniteMagnitude
         )
         textView.maxSize = NSSize(
@@ -49,9 +96,12 @@ struct EditorTextView: NSViewRepresentable {
         textView.font = font
         textView.textColor = .textColor
         textView.backgroundColor = .clear
-        textView.drawsBackground = false
+        textView.drawsBackground = true
         textView.insertionPointColor = .textColor
 
+        // Set alignment
+        textView.alignment = alignment
+
         // Set the text
         textView.string = text
 
@@ -84,11 +134,19 @@ struct EditorTextView: NSViewRepresentable {
         // Update font if changed
         if textView.font != font {
             textView.font = font
-            // Reapply font to entire text storage
             let range = NSRange(location: 0, length: textView.textStorage?.length ?? 0)
             textView.textStorage?.addAttribute(.font, value: font, range: range)
         }
 
+        // Update alignment if changed
+        if textView.alignment != alignment {
+            textView.alignment = alignment
+            let range = NSRange(location: 0, length: textView.textStorage?.length ?? 0)
+            let paragraphStyle = NSMutableParagraphStyle()
+            paragraphStyle.alignment = alignment
+            textView.textStorage?.addAttribute(.paragraphStyle, value: paragraphStyle, range: range)
+        }
+
         // Update text only if it actually changed (avoid feedback loops)
         if textView.string != text {
             let selectedRanges = textView.selectedRanges