perf: Add @micropython.native to rendering hot-paths in examples.

Apply the policy documented in this PR to the three examples with
tight pixel loops:

- tamagotchi.py: draw_character() — 4 nested loops, pixel by pixel
- spirit_level.py: fill_circle() — double loop with x*x + y*y test
- maze_game.py: draw_maze() — double loop over 11x11 grid

Author: nedseb

lib/bq27441/examples/tamagotchi.py

@@ -13,6 +13,7 @@
 import random
 from time import sleep_ms, ticks_diff, ticks_ms
 
+import micropython
 import ssd1327
 from bq27441 import BQ27441
 from machine import I2C, SPI, Pin
@@ -227,6 +228,7 @@ def wait_for_button():
     return None
 
 
+@micropython.native
 def draw_character(cx, cy, scale, sprite):
     """Draw a scaled pixel-art sprite on the display framebuf."""
     fb = display.framebuf

lib/ism330dl/examples/maze_game.py

@@ -18,6 +18,7 @@
 import random
 from time import sleep_ms
 
+import micropython
 import ssd1327
 from ism330dl import ISM330DL
 from machine import I2C, SPI, Pin
@@ -183,6 +184,7 @@ def cell_to_pixel(row, col):
     return SAFE_X + col * CELL_SIZE, SAFE_Y + row * CELL_SIZE
 
 
+@micropython.native
 def draw_maze(maze):
     """Draw all maze walls as filled rectangles."""
     for row in range(len(maze)):

lib/ism330dl/examples/spirit_level.py

@@ -9,6 +9,7 @@
 
 from time import sleep_ms
 
+import micropython
 import ssd1327
 from ism330dl import ISM330DL
 from machine import I2C, SPI, Pin
@@ -38,6 +39,7 @@
 POLL_RATE_MS = 20
 
 
+@micropython.native
 def fill_circle(fbuf, x0, y0, r, c):
     """Helper to draw a filled circle since framebuf lacks it natively."""
     for y in range(-r, r + 1):