Change default LED pin to 4 in esp32 ethernet builds

[softhack007]

change default LED pin to 4 in ethernet builds, and set AR default to "no mic" mode.
The "normal" default LED pin 16 is conflicting with pins needed by many ethernet boards, which can cause random crashes.

This should avoid some stability problems reported by ethernet users:

• WT32-ETH01 Error 8 Effect RAM depleted #5155 (comment)
• ESP-NOW must be disabled on ESP32 Ethernet boards that use ESP32 as PHY clock source; WLED-AP is affected too! #4703 (comment)
• GLEDOPTO Ethernet locks, stops responding after ESP-NOW sync send #5210
• Crashes when trying to save LED configuration (esp32 ethernet) #5322

Ethernet-related ESP-NOW and WIFI AP problems are not addressed by this PR.

Summary by CodeRabbit

• Bug Fixes

  • Prevents LED pin conflicts on Ethernet-enabled ESP32 boards by changing the default LED pin when Ethernet is active, improving startup reliability.

• Chores

  • Adds build-time options to control pin allocation and data-pin count.
  • Re-enables ESP-NOW by default while preserving a note about its interaction with Ethernet.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

Added build flags in platformio.ini and made DEFAULT_LED_PIN conditional: it becomes 4 when WLED_USE_ETHERNET is defined (with a compile-time warning), otherwise 16.

Changes

Cohort / File(s)	Summary
Build configuration platformio.ini	Added build flags: -D SR_DMTYPE=-1, -D DATA_PINS=4; removed active -D WLED_DISABLE_ESPNOW (left as comment/note about ESP‑NOW vs Ethernet).
Constants / Macros wled00/const.h	DEFAULT_LED_PIN now defined as 4 when WLED_USE_ETHERNET is set (emit compile‑time warning), otherwise 16. Replaced prior unconditional definition.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• DedeHai
• blazoncek

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: modifying the default LED pin to GPIO4 for ESP32 Ethernet builds to resolve pin conflicts.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@platformio.ini`:
- Line 514: Replace the incorrect preprocessor flag SR_DTYPE with the correct
flag SR_DMTYPE in the platformio build defines: change the define that currently
reads SR_DTYPE to SR_DMTYPE so the Audio Reactive code (referenced by
audio_reactive.cpp and its SR_DMTYPE checks) receives the intended -1 value to
disable pin allocation at startup (i.e., use -D SR_DMTYPE=-1).

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@platformio.ini`:
- Line 516: The platformio.ini change enabled ESP-NOW by default by removing the
-D WLED_DISABLE_ESPNOW flag which can crash Ethernet-only boards using
ETH_CLOCK_GPIO0_OUT/ETH_CLOCK_GPIO16_OUT/ETH_CLOCK_GPIO17_OUT; either restore
the default-safe behavior by re-adding/commenting in -D WLED_DISABLE_ESPNOW with
a clear comment on how to enable ESP-NOW for compatible boards, or implement a
compile-time guard in the build/config logic (check WLED_USE_ETHERNET and
WLED_DISABLE_ESPNOW/ESP-NOW flags) to emit a build warning/error when
WLED_USE_ETHERNET is enabled without explicit confirmation that the board
supports ESP-NOW (reference symbols: -D WLED_DISABLE_ESPNOW, WLED_USE_ETHERNET,
ETH_CLOCK_GPIO0_OUT, ETH_CLOCK_GPIO16_OUT, ETH_CLOCK_GPIO17_OUT).