[M5] verify-curated-db.sh + boost recipe (header-only)

CHANGELOG.md

@@ -87,6 +87,23 @@ All notable changes to cargoxx will be documented in this file.
   branch when the lockfile carries no rev.
 - `util::satisfies` treats `version == "*"` as a match against any
   range, mirroring the existing `range == "*"` shortcut.
+- `scripts/verify-curated-db.sh` plus per-package using-snippets at
+  `scripts/curated-snippets/<pkg>.cpp`. For each curated package the
+  script scaffolds a fresh project, `cargoxx add`s the dep, drops in a
+  snippet that exercises the library's API, and runs `cargoxx build`,
+  asserting the binary is produced. 21/25 packages pass against
+  `nixos-unstable`; the remaining 4 are documented as skipped:
+  `catch2`/`gtest` (their default linkdb targets ship their own
+  `main()` which collides with the snippet), `grpc` (needs `protobuf`
+  declared as a transitive dep — cross-package transitives are out of
+  v0.1 scope), `abseil-cpp` (nixpkgs builds it against libstdc++ while
+  our flake uses libc++ → ABI mismatch on the linker step).
+- `data/linkdb.json`: `boost` recipe is now header-only —
+  `find_package(Boost REQUIRED)` + `Boost::headers`. Boost 1.89's
+  `BoostConfig.cmake` searches for separately-installed
+  `boost_<comp>Config.cmake` files that nixpkgs doesn't ship, so
+  the previous `COMPONENTS` form failed at configure time.
+  Linkdb-component tests now use `abseil-cpp` for component coverage.
 - `cargoxx remove <pkg>` drops a declared dep from `Cargoxx.toml`,
   errors when the dep is not declared. Other deps are preserved.
 - End-to-end verified on a freshly-scaffolded project. `tests/cmd_add.cpp`