feat: add V2 foundation crates as stacked delivery base

.changeset/v2-foundation-crates.md

@@ -0,0 +1,5 @@
+---
+"tracedecay": patch
+---
+
+Land the stacked V2 foundation: ten workspace crates (api, application, host-integration, hooks, policy, private-fs, rusqlite-runtime, store, temporal-query, tool-catalog) and the V2 domain contracts, with protobuf node kinds now unconditional graph vocabulary. Hook spool roots are refused unless private to the current owner (and gain a private ACL on Windows), and Windows lock contention in the hook admission ledger and storage sidecar locks is typed as busy/contended instead of surfacing as I/O errors.

.github/workflows/ci.yml

@@ -266,6 +266,11 @@ jobs:
           npm install --global "@ast-grep/cli@$env:AST_GREP_VERSION"
           ast-grep --version
 
+      # The architecture tests exec `cargo metadata` at runtime; without an
+      # installed toolchain the rustup shim starts a mid-test component
+      # download that flakes. Install up front like the build job does.
+      - uses: dtolnay/rust-toolchain@stable
+
       - name: Install cargo-nextest
         uses: taiki-e/install-action@nextest