[style](trx-rs): fix clippy warnings for -D warnings CI

The CI lint job runs clippy with -D warnings, which surfaced a set of
existing warnings across decoders, the client, and the soapysdr backend.
Resolve them so the workspace is clean under the enforced lint level:

- collapsible_match / identity_op / needless_range_loop / same_item_push
  in trx-rds, trx-wspr, trx-vdes, trx-wefax, trx-aprs (mostly tests)
- field_reassign_with_default -> struct-update syntax in trx-client config
  tests
- assign_op_pattern, useless vec!, and test-module ordering picked up by
  cargo clippy --fix in trx-client and the soapysdr WFM tests

No behaviour changes; all affected crates' tests pass.

Assisted-By: Claude Code (claude-opus-4)
Claude-Session: https://claude.ai/code/session_01NFpGtGTWUEYXLwZeZs2RAV
Signed-off-by: Stan Grams <sjg@haxx.space>

src/decoders/trx-aprs/src/lib.rs

@@ -638,7 +638,7 @@ mod tests {
         for (i, &ch) in b"N0CALL".iter().enumerate() {
             addr[i] = ch << 1;
         }
-        addr[6] = (0 << 1) | 1; // SSID=0, last=true
+        addr[6] = 1; // SSID=0, last=true
 
         let decoded = decode_ax25_address(&addr, 0);
         assert_eq!(decoded.call, "N0CALL");
@@ -652,7 +652,7 @@ mod tests {
         for (i, &ch) in b"SP2SJG".iter().enumerate() {
             addr[i] = ch << 1;
         }
-        addr[6] = (5 << 1) | 0; // SSID=5, last=false
+        addr[6] = 5 << 1; // SSID=5, last=false
 
         let decoded = decode_ax25_address(&addr, 0);
         assert_eq!(decoded.call, "SP2SJG");
@@ -667,7 +667,7 @@ mod tests {
         for (i, &ch) in b"W1AW  ".iter().enumerate() {
             addr[i] = ch << 1;
         }
-        addr[6] = (0 << 1) | 1;
+        addr[6] = 1;
 
         let decoded = decode_ax25_address(&addr, 0);
         assert_eq!(decoded.call, "W1AW");
@@ -691,8 +691,8 @@ mod tests {
         for &ch in src_bytes.as_bytes().iter().take(6) {
             frame.push(ch << 1);
         }
-        frame.push((0 << 1) | 1); // SSID=0, last=true
-                                  // Control + PID
+        frame.push(1); // SSID=0, last=true
+                       // Control + PID
         frame.push(0x03); // UI frame
         frame.push(0xF0); // No layer-3 protocol
                           // Info field

src/decoders/trx-rds/src/lib.rs

@@ -632,32 +632,17 @@ impl Candidate {
             }
             let segment = usize::from((block_b & 0x0003) as u8);
             let di = ((block_b >> 2) & 0x1) != 0;
-            match segment {
-                0 => {
-                    if self.state.dynamic_pty != Some(di) {
-                        self.state.dynamic_pty = Some(di);
-                        changed = true;
-                    }
-                }
-                1 => {
-                    if self.state.compressed != Some(di) {
-                        self.state.compressed = Some(di);
-                        changed = true;
-                    }
-                }
-                2 => {
-                    if self.state.artificial_head != Some(di) {
-                        self.state.artificial_head = Some(di);
-                        changed = true;
-                    }
-                }
-                3 => {
-                    if self.state.stereo != Some(di) {
-                        self.state.stereo = Some(di);
-                        changed = true;
-                    }
-                }
-                _ => {}
+            let di_flag = Some(di);
+            let slot = match segment {
+                0 => &mut self.state.dynamic_pty,
+                1 => &mut self.state.compressed,
+                2 => &mut self.state.artificial_head,
+                3 => &mut self.state.stereo,
+                _ => unreachable!("segment is masked to two bits"),
+            };
+            if *slot != di_flag {
+                *slot = di_flag;
+                changed = true;
             }
             let [b0, b1] = block_d.to_be_bytes();
             self.ps_bytes[segment * 2] = sanitize_text_byte(b0);
@@ -1458,9 +1443,9 @@ mod tests {
         }
 
         // BPSK modulate onto the 57 kHz subcarrier.
-        for t in 0..n {
+        for (t, sample) in shaped.iter_mut().enumerate().take(n) {
             let phase = TAU * RDS_SUBCARRIER_HZ * t as f32 / sample_rate;
-            shaped[t] *= phase.cos();
+            *sample *= phase.cos();
         }
         shaped
     }

src/decoders/trx-vdes/src/crc.rs

@@ -134,9 +134,7 @@ mod tests {
             .flat_map(|&b| (0..8).rev().map(move |i| (b >> i) & 1))
             .collect();
         // Append wrong CRC
-        for _ in 0..16 {
-            bits.push(0);
-        }
+        bits.resize(bits.len() + 16, 0);
         assert!(!check_crc16(&bits));
     }
 

src/decoders/trx-vdes/src/link_layer.rs

@@ -346,8 +346,8 @@ mod tests {
         write_bits(&mut bits, 12, 32, 123456); // source_id
         write_bits(&mut bits, 44, 11, 20); // data_count = 20
                                            // Fill some payload
-        for i in 55..75 {
-            bits[i] = (i % 2) as u8;
+        for (i, bit) in bits.iter_mut().enumerate().take(75).skip(55) {
+            *bit = (i % 2) as u8;
         }
         append_crc(&mut bits);
 

src/decoders/trx-wefax/src/image.rs

@@ -374,8 +374,8 @@ mod tests {
         let (y, m, d, h, mi, _) = unix_to_utc(1775055000);
         assert_eq!(y, 2026);
         // Just verify reasonable values without asserting exact date.
-        assert!(m >= 1 && m <= 12);
-        assert!(d >= 1 && d <= 31);
+        assert!((1..=12).contains(&m));
+        assert!((1..=31).contains(&d));
         assert!(h < 24);
         assert!(mi < 60);
     }

src/decoders/trx-wefax/src/phase.rs

@@ -161,10 +161,8 @@ mod tests {
 
         for line_idx in 0..20 {
             let mut line = vec![1.0f32; spl];
-            for j in pulse_start..pulse_start + pw {
-                if j < spl {
-                    line[j] = 0.0;
-                }
+            for slot in line.iter_mut().skip(pulse_start).take(pw) {
+                *slot = 0.0;
             }
             let result = det.process(&line);
             if let Some(offset) = result {

src/decoders/trx-wspr/src/protocol.rs

@@ -483,7 +483,7 @@ mod tests {
         let c4 = idx27(b'T');
         let c5 = idx27(b' ');
         let n1 = ((c0 * 36 + c1) * 10 + c2) * 27u32.pow(3) + c3 * 27u32.pow(2) + c4 * 27 + c5;
-        let m1 = (179 - 10 * 5 - 2) * 180 + 10 * 13 + 0; // FN20
+        let m1 = (179 - 10 * 5 - 2) * 180 + 10 * 13; // FN20 (final term is 0)
         let power_code = 37u32;
 
         let mut input_bits = [0u8; NBITS];
@@ -530,8 +530,8 @@ mod tests {
     fn interleave_deinterleave_roundtrip() {
         // Create a sequence of distinguishable values
         let mut original = [0u8; NSYMS];
-        for i in 0..NSYMS {
-            original[i] = (i % 256) as u8;
+        for (i, slot) in original.iter_mut().enumerate() {
+            *slot = (i % 256) as u8;
         }
 
         let interleaved = interleave(&original);