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-wasm/Cargo.toml

@@ -8,13 +8,14 @@ description = "CalcPad calculation engine compiled to WebAssembly"
 crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-calcpad-engine = { path = "../calcpad-engine" }
+calcpad-engine = { path = "../calcpad-engine", default-features = false }
 wasm-bindgen = "0.2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 serde-wasm-bindgen = "0.6"
 js-sys = "0.3"
 chrono = "0.4"
+getrandom = { version = "0.2", features = ["js"] }
 
 [dev-dependencies]
 wasm-bindgen-test = "0.3"