Rename crate to mytheclipse and flatten workspace to single crate

- Rename corex -> mytheclipse (corex name taken on crates.io by an
  unrelated crate published by David-Kunz in 2023)
- Flatten corex + corex-core workspace into a single crate; all modules
  (context/error/io/compute/bg) now live directly under src/
- Update Cargo.toml metadata: real repo URL, docs.rs, author
- Update README, example, doc comments, tracing span names
- Fix CI: single package dry-run (corex-core no longer separate)
- Fix publish workflow: single cargo publish step

.gitignore

@@ -1,15 +1,9 @@
 # Cargo build artifacts
 /target
-/crates/*/target
-
-# corex is a library workspace: the lockfile is not committed, per Rust's
-# convention for libraries (binaries/applications should commit theirs).
-# Cargo regenerates it locally and in CI on every build.
-Cargo.lock
 
 # Editor / OS noise
 .DS_Store
 Thumbs.db
 *.swp
 .idea/
-.vscode/
+.vscode/