esp32s3: replace inline ISR with full interrupt vector handler

Replace the minimal inline ISR (which only disabled INTENABLE) with a
full level-1 interrupt handler that saves/restores the interrupted
context and dispatches to Go's handleInterrupt.

The handler uses callx4 (not callx0) to call into Go code because:
- callx0 does not set PS.CALLINC, so the Go function's entry
  instruction uses stale CALLINC from the interrupted code, causing
  wrong window rotation and a garbage stack pointer.
- callx4 explicitly sets CALLINC=1, and our frame pointer (a1) is
  outside the callee's register window so it is preserved.

Also updates the USB Serial/JTAG ISR to disable INT_ENA (peripheral
level) instead of relying on INTENABLE, and adds signalInterrupt to
the dispatcher so sleepTicks can be woken by any interrupt.

src/runtime/interrupt/interrupt_esp32s3.go

@@ -115,6 +115,9 @@ func handleInterrupt() {
 		}
 	}
 
+	// Signal to sleepTicks that an interrupt has occurred.
+	signalInterrupt()
+
 	inInterrupt = false
 }
 
@@ -180,6 +183,9 @@ func callHandler(n int) {
 //go:linkname callHandlers runtime/interrupt.callHandlers
 func callHandlers(num int)
 
+//go:linkname signalInterrupt runtime.signalInterrupt
+func signalInterrupt()
+
 var errInterruptRange = constError("interrupt for ESP32-S3 must be in range 6 through 30")
 
 type constError string