chore(ci): drop unnecessary runt-cli build from Python integration tests (#1273)

* perf(ci): pre-build notebook crate to reduce feature-unification recompilation

Add -p notebook to the initial cargo build in build-linux and build
matrix jobs so the later tauri/full-workspace builds find deps cached.
Also drop unnecessary -p runt-cli from runtimed-py-integration.

* fix(ci): build notebook after sidecar copy, not in same invocation

notebook's build.rs (tauri_build) requires sidecar binaries to exist
in crates/notebook/binaries/ at build time. Split into: build sidecars
→ copy → build notebook, so the cache is warm for the tauri step.

* revert(ci): remove notebook pre-build steps, keep runt-cli cleanup

The notebook pre-build didn't help — cargo tauri build --ci adds
custom-protocol which invalidates the notebook crate anyway, so it
compiled twice (250s wasted). Revert to original flow.

Keep the runt-cli removal from runtimed-py-integration since that
job only needs the runtimed binary.

Author: rgbkrk

.github/workflows/build.yml

@@ -655,7 +655,7 @@ jobs:
         uses: astral-sh/setup-uv@v7
 
       - name: Build runtimed binary
-        run: cargo build --release -p runtimed -p runt-cli
+        run: cargo build --release -p runtimed
 
       - name: Build runtimed-py
         working-directory: python/runtimed