Fix D key starting OINK instead of DNH from IDLE

[albertonoys]

Problem:

• Pressing D in IDLE mode starts OINK_MODE instead of DNH_MODE
• Expected: IDLE → (D key) → DNH_MODE
• Actual: IDLE → (D key) → DNH_MODE → OINK_MODE (immediately)

Root cause:

• IDLE handler sets DNH_MODE but continues executing handleInput()
• DNH mode handler runs in the same frame
• DNH handler detects D key still pressed and switches to OINK_MODE
• dWasPressed_dnh doesn't help because it's the first frame in DNH mode
• Mode transition completes but input handler doesn't exit

Solution:

• Add return after setMode(PorkchopMode::DNH_MODE) in IDLE handler
• Prevents DNH handler from running until next frame
• Matches existing pattern from OINK↔DNH transitions

Testing:

• Tested on M5Cardputer ADV
• Verified D key from IDLE now correctly enters DNH_MODE
• Verified D key still toggles between OINK↔DNH as expected

Files changed:

• src/core/porkchop.cpp: Added return statement at line 542

[albertonoys]

Closing PR since this bug was already fixed.