chore: upgrade to Rust 1.92.0 (#8860)

**Summary**
- Upgrade Rust toolchain used by CI to 1.92.0.
- Address new clippy `derivable_impls` warnings by deriving `Default`
for enums across protocol, core, backend openapi models, and
windows-sandbox setup.
- Tidy up related test/config behavior (originator header handling, env
override cleanup) and remove a now-unused assignment in TUI/TUI2 render
layout.

**Testing**
- `just fmt`
- `just fix -p codex-tui`
- `just fix -p codex-tui2`
- `just fix -p codex-windows-sandbox`
- `cargo test -p codex-tui`
- `cargo test -p codex-tui2`
- `cargo test -p codex-windows-sandbox`
- `cargo test -p codex-core --test all`
- `cargo test -p codex-app-server --test all`
- `cargo test -p codex-mcp-server --test all`
- `cargo test --all-features`

codex-rs/windows-sandbox-rs/src/setup_main_win.rs

@@ -76,19 +76,14 @@ struct Payload {
     refresh_only: bool,
 }
 
-#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, Default)]
 #[serde(rename_all = "kebab-case")]
 enum SetupMode {
+    #[default]
     Full,
     ReadAclsOnly,
 }
 
-impl Default for SetupMode {
-    fn default() -> Self {
-        Self::Full
-    }
-}
-
 fn log_line(log: &mut File, msg: &str) -> Result<()> {
     let ts = chrono::Utc::now().to_rfc3339();
     writeln!(log, "[{ts}] {msg}")?;