ci(release): decide changeset coverage from turbo's build hashes

.changeset/README.md

@@ -7,14 +7,18 @@ one with:
 pnpm change --bump <none|patch|minor|major> --summary "<changelog entry>" [<pkg>...]
 ```
 
-- A pull request that changes a publishable package's path ships an intent
-  here; the changeset check fails without one.
+- A pull request whose head moves a publishable package's turbo `build` hash
+  from the base ships an intent naming that package (`release.jsonc` `gate`);
+  the changeset check fails without one. Files outside the package can move
+  that hash too, for example `turbo.json`'s `build` task or `globalEnv`, or the
+  root `package.json`'s dependencies. Such a pull request names the package,
+  with `none` when its tarball does not change.
 - `none` records a change that needs no release. A `none` on a change a
   consumer can see is the silent non-release the check exists to catch.
 - `@systemfsoftware/api-extractor` is at 0.0.0 and the tag
   `@systemfsoftware/api-extractor@v0.0.0` exists. While both hold, a pull
-  request that changes `packages/api-extractor` ships a non-`none` intent for
-  it, because a `none` on a change to its tarball makes Release refuse with
+  request that changes its tarball ships a non-`none` intent for it, because a
+  `none` on a change to its tarball makes Release refuse with
   `tag-integrity-mismatch`. The tag is deleted only in the change that moves
   the version off 0.0.0.
 - The release PR consumes pending intents with `pnpm version -r`, writes each

release.jsonc

@@ -8,7 +8,7 @@
   "versioning": {
     "strategy": "changesets",
   },
-  // A change under a package's directory needs an intent naming it. The turbo
-  // gate dry-runs turbo at the base, which a base without turbo.json refuses.
-  "gate": { "strategy": "paths" },
+  // A pull request whose head moves a publishable package's turbo `build` hash
+  // away from the base ships an intent naming that package.
+  "gate": { "strategy": "turbo", "task": "build" },
 }