chore: raise rust-version floor to 1.88; fix 1.88 clippy lints

The 1.85 claim was already false at the dependency level: the resolved
lockfile pulls icu_* 2.x (MSRV 1.86) and wasip2 1.87 transitively via
jsonschema -> idna, so 1.85 toolchains cannot build 0.7.0 regardless of
what Cargo.toml declares. Raising the floor to 1.88 aligns with the
noq QUIC path (per the ecosystem MSRV audit) and breaks no downstream
that could build the crate before.

- Cargo.toml: rust-version 1.85 -> 1.88 (version-line bump deferred to
  release time; semver-checks passes either way)
- src/channels/mux.rs: collapse else { if .. } (collapsible_else_if)
- src/core/types.rs, src/registry/registration.rs: inline format args
  (uninlined_format_args)

Verification:
- 1.88: cargo test --locked (631 pass), clippy --all-targets -D warnings
- stable 1.94: test --locked, clippy -D warnings, --all-features, fmt,
  doc --no-deps
- wasm32-unknown-unknown: cargo check
- cargo semver-checks check-release: no semver update required

Cargo.toml

@@ -2,7 +2,7 @@
 name = "alkcall"
 version = "0.7.0"
 edition = "2021"
-rust-version = "1.85"
+rust-version = "1.88"
 license = "MIT OR Apache-2.0"
 description = "Call + channels RPC: structured JSON operations, streaming subscriptions, service discovery, and N-channel multiplexing over one transport stream"
 readme = "README.md"

src/channels/mux.rs

@@ -151,10 +151,8 @@ impl MuxRunner {
                                     );
                                 }
                                 break;
-                            } else {
-                                if let Err(e) =
-                                    super::wire::write_chunk(&mut *writer, channel_id, &payload)
-                                        .await
+                            } else if let Err(e) =
+                                super::wire::write_chunk(&mut *writer, channel_id, &payload).await
                             {
                                 tracing::warn!(
                                     channel_id,
@@ -164,7 +162,6 @@ impl MuxRunner {
                                 break;
                             }
                         }
-                        }
                         None => {
                             let mut writer = writer.lock().await;
                             let _ = super::wire::write_eof(&mut *writer, channel_id).await;

src/core/types.rs

@@ -749,7 +749,7 @@ mod tests {
     #[test]
     fn capabilities_debug_redacts_entries() {
         let caps = Capabilities::new().with_api_key("google", "sekrit".to_string());
-        let s = format!("{:?}", caps);
+        let s = format!("{caps:?}");
         assert!(s.contains("redacted"));
         assert!(!s.contains("sekrit"));
     }
@@ -757,7 +757,7 @@ mod tests {
     #[test]
     fn secret_debug_redacts() {
         let secret = Secret::new("hidden".to_string());
-        assert_eq!(format!("{:?}", secret), "[REDACTED]");
+        assert_eq!(format!("{secret:?}"), "[REDACTED]");
     }
 
     #[test]

src/registry/registration.rs

@@ -807,13 +807,13 @@ pub(crate) fn extract_json_pointer(input: &Value, path: &str) -> Option<String>
         return None;
     }
     let pointer = if let Some(rest) = trimmed.strip_prefix('/') {
-        format!("/{}", rest)
+        format!("/{rest}")
     } else {
         let dotted = trimmed.replace('.', "/");
         if let Some(rest) = dotted.strip_prefix('/') {
-            format!("/{}", rest)
+            format!("/{rest}")
         } else {
-            format!("/{}", dotted)
+            format!("/{dotted}")
         }
     };
     input