docs: reorganize into en/ru and add English translation

docs/en/README.md

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+# Glint Runtime — Documentation
+
+Backend for executing compiled bytecode (.glbc) of the Glint UI framework. Loads bytecode, interprets VDOM, applies CSS-like styles, executes Rhai scripts, and renders the result via Iced (native GPU-accelerated GUI).
+
+## Project Structure
+
+- `src/main.rs` — entry point, CLI parsing
+- `src/lib.rs` — public API of the crate
+- `src/app.rs` — GlintApp: Iced application, update/view
+- `src/cli.rs` — CLI commands compile/run
+- `src/renderer.rs` — Iced widgets: Element → iced::Element conversion
+- `src/perf.rs` — PerfScope: performance measurement by phases
+- `src/interpreter/mod.rs` — Interpreter: bytecode loading, VDOM eval
+- `src/interpreter/types.rs` — Element, VNode, FlatVDom, Value, InternedStr, Document
+- `src/interpreter/style.rs` — StyleSheet, StyleRule, StyleIndex, StyleCache, ComputedStyle
+- `src/interpreter/reactive.rs` — ReactiveTracker: dependency graph
+- `src/interpreter/rhei.rs` — RheiContext: Rhai script integration
+- `src/interpreter/reader.rs` — Reader: .glbc bytecode reading
+- `src/interpreter/opcodes.rs` — OP_* bytecode constants
+
+## Related Repositories
+
+- `glt` (compiler .gltm/.glts → .glbc)
+
+## Key Concepts
+
+- **Document** — loaded .glbc file: Element tree, style sheet, variables
+- **Element** — VDOM node: type_name, properties, children, computed_style, element_id, content_hash
+- **VDOM** — virtual tree, result of bytecode interpretation
+- **StyleSheet** — style sheet with indexed lookup and computed style cache
+- **ReactiveTracker** — tracks element → variable dependencies, dirty_set
+- **RheiContext** — compiles and executes Rhai scripts, caches AST
+- **ComputedStyle** — result of applying CSS rules: ~40 fields (color, padding, font-size, etc.)
+
+## Optimization Phases
+
+See [ARCHITECTURE-IMPROVEMENT-PLAN.md](../ARCHITECTURE-IMPROVEMENT-PLAN.md).
+
+**Implemented:** phases 3–8, 10, 9.1–9.2 (content_hash, stable Iced widget IDs).
+
+**Remaining:**
+| Phase | Description | Estimated Speedup |
+|-------|-------------|-------------------|
+| 0 | Profiling (bench, flamegraph) | — |
+| 1 | Typed Values in styles instead of HashMap<String, String> | 2–3× |
+| 2 | String interning for hot paths | 1.5–2× |
+| 9.3 | Iced widget cache by content_hash | 1.5–2× (render) |