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

.github/workflows/publish.yml

@@ -11,13 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
-      - name: Publish corex-core
-        run: cargo publish -p corex-core --allow-dirty --no-verify
+      - name: Publish mytheclipse
+        run: cargo publish --allow-dirty --no-verify
         env:
-          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
-      - name: Wait for crates.io indexing
-        run: sleep 30
-      - name: Publish corex
-        run: cargo publish -p corex --allow-dirty --no-verify
-        env:
-          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}