RDKDEV-1421 Add thunderUI Documentation

[gourivarma3]

RDKDEV-1421

[gourivarma3]

Added README.md for thunderUI
I have read the CLA Document and I hereby sign the CLA

[Copilot]

Pull request overview

Adds a comprehensive technical README under docs/ describing ThunderUI’s purpose, architecture, module structure, and runtime/build configuration to help developers understand and operate the project.

Changes:

• Introduces a full ThunderUI design/architecture overview (including Mermaid diagrams).
• Documents module responsibilities and component interactions (JSON-RPC/WebSocket + REST fallback).
• Describes configuration and persistence behavior (conf/env/localStorage).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (6)

docs/README.md:82

• This makes it sound like Node ≥17 is always handled automatically, but the automatic --openssl-legacy-provider wiring only happens when building via CMake (it sets NODE_OPTIONS). Clarify the scope so developers running npm scripts directly know what to expect.

- **Build Dependencies**: Node.js (≥ 17 handled automatically with OpenSSL legacy provider), npm, Webpack 4, ThunderJS v1.2.4, `copy-webpack-plugin`, `css-loader`, `style-loader`, `dotenv-webpack`.

docs/README.md:216

• The docs describe cache_period as an active API cache setting, but ThunderUI currently doesn't use it anywhere (it only exists as a constant in conf.js). Adjust this row so readers don't assume it has runtime effect.

| `conf.js`                        | Static configuration values compiled into the bundle: polling interval, API cache period, and the default start plugin.                                                                                                                                                 | `src/js/conf.js`                    |

docs/README.md:326

• cache_period is currently not used in the codebase (only defined in src/js/conf.js). Consider marking it as currently unused here to keep the configuration documentation accurate.

| `src/js/conf.js`        | Compiled into the bundle. Sets polling interval, API cache period, and default start plugin.                           | Edit source before building                                                  |

docs/README.md:334

• cache_period is described as controlling API response caching, but there is no implementation using this value (it’s only defined in src/js/conf.js). Update the description to reflect its current status or link it to the code that uses it.

| `cache_period`     | int    | `500`          | Duration in milliseconds during which the WPE API will serve a cached response to prevent excessive requests. Defined in `conf.js`.            |

docs/README.md:336

• The runtime fallback is resolveHostnamePort() (hostname + port, defaulting port 80 when absent), not just window.location.hostname. Tweaking this wording makes the behavior match src/js/helpers.js.

| `HOST`             | string | `127.0.0.1`    | Target device IP address used for development builds. Set in `.env.local` (not deployed). Falls back to `window.location.hostname` at runtime. |

docs/README.md:85

• cache_period is documented as an active runtime setting here, but it is not referenced anywhere outside src/js/conf.js (the API layer does not currently use it). Mark it as currently unused (or implement the caching/throttling behavior in code).

This issue also appears in the following locations of the same file:

• line 216
• line 326
• line 334

- **Configuration Files**: `conf.js` (compiled into bundle) — sets `refresh_interval` (5000 ms), `cache_period` (500 ms), and `startPlugin` (Controller). At build time, an optional `.env.local` file supplies `HOST` for local development builds.

[gourivarma3]

The review comments are now addressed