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>

.coderabbit.yaml

@@ -0,0 +1,68 @@
+# yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json
+#
+# CodeRabbit configuration — references existing guideline files to avoid
+# duplicating conventions.  See:
+#   .github/copilot-instructions.md   — project overview & general rules
+#   .github/cpp.instructions.md       — C++ coding conventions
+#   .github/web.instructions.md       — Web UI coding conventions
+#   .github/cicd.instructions.md      — GitHub Actions / CI-CD conventions
+#   .github/esp-idf.instructions.md   — ESP-IDF / chip-specific coding guidelines
+#                                       (apply when code directly uses ESP-IDF APIs:
+#                                        esp_idf_*, I2S, RMT, ADC, GPIO, heap_caps, etc.)
+#
+# NOTE: This file must be committed (tracked by git) for CodeRabbit to read
+# it from the repository.  If it is listed in .gitignore, CodeRabbit will
+# not see it and these settings will have no effect.
+
+language: en-US
+
+reviews:
+  path_instructions:
+    - path: "**/*.{cpp,h,hpp,ino}"
+      instructions: >
+        Follow the C++ coding conventions documented in .github/cpp.instructions.md
+        and the general project guidelines in .github/copilot-instructions.md.
+        If the code under review directly uses ESP-IDF APIs (e.g. heap_caps_malloc,
+        I2S, RMT, ADC, GPIO, esp_timer, or any esp_idf_* / soc_* symbols), also
+        apply the guidelines in .github/esp-idf.instructions.md.
+
+        Key rules: 2-space indentation (no tabs), camelCase functions/variables,
+        PascalCase classes, UPPER_CASE macros. Mark WLED-MM-specific changes with
+        `// WLEDMM` comments. No C++ exceptions — use return codes and debug macros.
+
+        Hot-path optimization guidelines (attributes, uint_fast types, caching,
+        unsigned range checks) apply from pixel set/get operations downward —
+        NOT to effect functions in FX.cpp, which have diverse contributor styles.
+
+    - path: "wled00/data/**"
+      instructions: >
+        Follow the web UI conventions documented in .github/web.instructions.md.
+
+        Key rules: indent HTML and JavaScript with tabs, CSS with tabs or spaces.
+        Files here are built into wled00/html_*.h by tools/cdata.js — never
+        edit those generated headers directly.
+
+    - path: "wled00/html_*.h"
+      instructions: >
+        These files are auto-generated from wled00/data/ by tools/cdata.js.
+        They must never be manually edited or committed. Flag any PR that
+        includes changes to these files.
+
+    - path: "usermods/**"
+      instructions: >
+        Usermods are community add-ons following the upstream WLED 0.15.x style.
+        Each usermod lives in its own directory under usermods/ and is implemented
+        as a .h file that is pulled in by wled00/usermods_list.cpp (guarded by
+        #ifdef). Usermods do not use library.json. Follow the same C++ conventions
+        as the core firmware (.github/cpp.instructions.md).
+
+    - path: ".github/workflows/*.{yml,yaml}"
+      instructions: >
+        Follow the CI/CD conventions documented in .github/cicd.instructions.md.
+
+        Key rules: 2-space indentation, descriptive name: on every workflow/job/step.
+        Third-party actions must be pinned to a specific version tag — branch pins
+        such as @main or @master are not allowed. Declare explicit permissions: blocks
+        scoped to least privilege. Never interpolate github.event.* values directly
+        into run: steps — pass them through an env: variable to prevent script
+        injection. Do not use pull_request_target unless fully justified.