feat: add comprehensive skills and agents for Rust development (#1573)

.cursor/agents/rust-changelog.md

@@ -0,0 +1,38 @@
+# rust-changelog
+
+Fetch Rust version changelog from releases.rs.
+
+## URL
+
+`releases.rs/docs/<version>/` (e.g., `1.85`, `1.84.1`)
+
+## Fetch
+
+Use available tools to get releases.rs content.
+
+## Output
+
+```markdown
+## Rust <Version> Release Notes
+
+**Release Date:** <date>
+
+### Language Features
+- feature: desc
+
+### Standard Library
+- new/stabilized API: desc
+
+### Cargo
+- change: desc
+
+### Breaking Changes
+- note: desc
+```
+
+## Validation
+
+1. Content contains version number
+2. Has "Language" or "Features" sections
+3. Not "version not found"
+4. On failure: "Version {v} does not exist or fetch failed"