Revise copilot-instructions.md: consolidate, shorten, extract and extend language-specific rules (#353)

Revise copilot-instructions.md: consolidate redundant sections, extract language-specific rules
* Added comprehensive internal documentation files establishing coding standards and development workflows for C++, Web UI, CI/CD, and ESP-IDF components.
* Implemented CodeRabbit configuration to enforce repository-specific code review guidance and quality standards across pull requests.
* Documented development workflow procedures and contribution expectations to streamline the development process and improve code consistency.

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: softhack007 <91616163+softhack007@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

.github/web.instructions.md

@@ -0,0 +1,28 @@
+---
+applyTo: "wled00/data/**"
+---
+# Web UI Coding Conventions
+
+## Formatting
+
+- Indent **HTML and JavaScript** with **tabs**
+- Indent **CSS** with **tabs** or **spaces**
+
+## JavaScript Style
+
+- **camelCase** for functions and variables: `gId()`, `selectedFx`, `currentPreset`
+- Abbreviated helpers are common: `d` for `document`, `gId()` for `getElementById()`
+- Mark WLED-MM additions with `// WLEDMM` comments
+
+## Key Files
+
+- `index.htm` — main interface
+- `index.js` — functions that manage / update the main interface
+- peek.js, liveview*.htm - live preview in main interface
+- `settings*.htm` — configuration pages
+- `*.css` — stylesheets (inlined during build)
+
+## Build Integration
+
+Files in this directory are processed by `tools/cdata.js` into `wled00/html_*.h` headers.
+Run `npm run build` after any change. **Never edit the generated `html_*.h` files directly.**