Remove waterfall from all modes except listening post

Reverts IQ pipeline and removes syncWaterfallToFrequency calls from
pager, sensor, rtlamr, DMR, SSTV, and SSTV general modes. Waterfall
is now exclusive to listening post mode.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

utils/sdr/base.py

@@ -186,36 +186,6 @@ class CommandBuilder(ABC):
         """Return hardware capabilities for this SDR type."""
         pass
 
-    def build_raw_capture_command(
-        self,
-        device: SDRDevice,
-        frequency_mhz: float,
-        sample_rate: int,
-        gain: Optional[float] = None,
-        ppm: Optional[int] = None,
-        bias_t: bool = False
-    ) -> list[str]:
-        """
-        Build raw IQ capture command (for IQ-based waterfall during decoding).
-
-        Args:
-            device: The SDR device to use
-            frequency_mhz: Center frequency in MHz
-            sample_rate: Sample rate in Hz
-            gain: Gain in dB (None for auto)
-            ppm: PPM frequency correction
-            bias_t: Enable bias-T power (for active antennas)
-
-        Returns:
-            Command as list of strings for subprocess
-
-        Raises:
-            NotImplementedError: If the SDR type does not support raw capture
-        """
-        raise NotImplementedError(
-            f"Raw IQ capture not supported for {self.get_sdr_type().value}"
-        )
-
     @classmethod
     @abstractmethod
     def get_sdr_type(cls) -> SDRType: