[Configuration] Enable MPC_EDIT_MENU and MPC_AUTOTUNE_MENU by default

[fanXbox]

Is your feature request related to a problem? Please describe.

Uncomment MPC_EDIT_MENU and MPC_AUTOTUNE_MENU by default inside the existing #if ENABLED(MPCTEMP) block, which is located in Configuration.h.

Currently, even if a user enables MPCTEMP, these two LCD menu options remain commented out within the same file. This forces users to manually search for and uncomment them to gain standalone calibration functionality.

By default-enabling these lines, anyone who turns on Model Predictive Control will immediately get the corresponding LCD options without extra manual steps. Since they are already wrapped inside #if ENABLED(MPCTEMP), this change is completely safe and will not waste flash memory for users who keep MPC disabled.

Are you looking for hardware support?

No response

Describe the feature you want

Currently, when a user enables Model Predictive Control (MPCTEMP) in Configuration.h, the corresponding LCD tuning menus (MPC_EDIT_MENU and MPC_AUTOTUNE_MENU) remain hidden by default.

This creates a friction point because users cannot perform the calibration directly from the printer's screen. Instead, they are forced to connect a computer to use an external G-code terminal or manually create a .gcode file just to run the autotune process, unless they remember to manually find and uncomment those lines.

Additional context

No response

[ellensp]

Marlin philosophy 101:

1. All options are off by default to minimise the firmware size and reduce build times.
2. Marlin is G-code controlled; all other input systems, such as LCDs, are secondary and completely optional.

Many users use OctoPrint and no LCD, Why should those options be on for them?

[fanXbox]

I understand that perspective, but following that logic to its ultimate conclusion would mean we should disable all LCD menus by default for every single feature in Marlin (e.g., hiding PID tuning, E-steps calibration, or bed leveling menus), forcing users to manually opt-in line-by-line for every UI element.
Standard Marlin practice for similar features (like PIDTEMP and PID_EDIT_MENU) is that if a user has an LCD enabled and opts into a temperature system, the standard tuning menus are available to them.
If a user controls the printer exclusively via PC/OctoPrint, they usually disable the LCD display entirely (the #define REPRAP_DISCOUNT_SMART_CONTROLLER line remains commented out) or disable only the menus, leaving only the status interface visible by uncommenting the #define NO_LCD_MENUS line.
By disabling the screen, all menu code is automatically stripped out by the compiler, saving maximum flash space.
Keeping MPC_EDIT_MENU and MPC_AUTOTUNE_MENU disabled by default inside an already explicit feature (MPCTEMP) creates an inconsistent user experience compared to how PID or other core systems are handled.