Separate RadioLib ISR events from main radio mode

[robekl]

Summary

This fixes the RadioLib wrapper ISR handoff by separating interrupt events from the main radio mode state.

Problem

RadioLibWrapper currently shares a single volatile uint8_t state between ISR and normal code:

• the RadioLib interrupt callback does state |= STATE_INT_READY
• main code repeatedly overwrites that same variable with assignments like state = STATE_IDLE, state = STATE_RX, and state = STATE_TX_WAIT

That is not an atomic synchronization scheme. volatile only prevents caching; it does not make read-modify-write operations safe. An interrupt can arrive between the load and store of one of those assignments, causing a completion event to be lost.

That can show up as missed send-complete / receive-complete notifications and inconsistent mode transitions.

Fix

This PR removes the overloaded shared state byte and splits the responsibilities:

• radio_mode is now main-context only and tracks IDLE, RX, or TX_WAIT
• pending_interrupt_events is ISR-owned and only records completion events
• the ISR only increments the pending-event counter
• main code claims and clears pending events atomically inside a very short interrupt-disabled section

The wrapper now reasons about:

• mode transitions using radio_mode
• interrupt completion using the claimed event count

instead of trying to encode both into one shared variable.

Why this fixes it

Main code no longer overwrites an ISR-owned bitfield. The ISR publishes completion events into its own channel, and the main loop claims them explicitly before acting.

That removes the lost-interrupt window that existed when the code mixed plain assignments and ISR-side bit-setting on the same byte.

Validation

Built successfully:

• Heltec_v3_repeater