Build break: main component does not compile espnow_frag.c

[airadier]

Summary

main/CMakeLists.txt does not include espnow_frag.c in idf_component_register(...), but espnow_comm.c calls espnow_fragment().

Impact

Firmware builds that include espnow_comm.c can fail at link time with unresolved symbols for fragmentation helpers.

Evidence

• main/CMakeLists.txt:2
• main/espnow_comm.c:93
• main/espnow_frag.c

Expected

The main firmware component should compile and link all sources it depends on.

Notes

Host-side test wiring already knows about espnow_frag.c, which suggests the source file was added later but not registered in the firmware component.