chore: fix clippy lints, sync MSRV, and bump to v0.1.19

- Update clippy.toml msrv from 1.83 to 1.85 to match Cargo.toml
- Mark `platform_suffix` and `Installer::with_dir` as `const fn`
- Bump workspace version from 0.1.18 to 0.1.19

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

Author: refcell

Cargo.toml

@@ -4,7 +4,7 @@ resolver = "2"
 
 [workspace.package]
 description = "Edge Language Compiler Workspace"
-version = "0.1.18"
+version = "0.1.19"
 edition = "2021"
 rust-version = "1.85"
 license = "MIT"

clippy.toml

@@ -1 +1 @@
-msrv = "1.83"
+msrv = "1.85"

crates/edgeup-lib/src/installer.rs

@@ -32,7 +32,7 @@ pub struct GithubAsset {
 /// Return the platform suffix matching the current OS and architecture.
 ///
 /// These correspond to the Rust target triples used in the release workflow.
-pub fn platform_suffix() -> &'static str {
+pub const fn platform_suffix() -> &'static str {
     #[cfg(all(target_os = "linux", target_arch = "x86_64"))]
     {
         "x86_64-unknown-linux-gnu"
@@ -119,7 +119,7 @@ impl Installer {
     /// Create an installer rooted at an arbitrary directory.
     ///
     /// Useful for testing without touching `~/.edgeup`.
-    pub fn with_dir(install_dir: PathBuf) -> Self {
+    pub const fn with_dir(install_dir: PathBuf) -> Self {
         Self { install_dir }
     }