fix(eng): trigger all emitter CI on any pnpm-workspace.yaml change (Azure#5059)

Fixes Azure#5010.

## Problem

`@typespec/http-client-python` is not a workspace package — it is
consumed from npm through the pnpm **catalog**, so bumping it only edits
the root `pnpm-workspace.yaml`.

pnpm attributes root-file changes to the **root package only**, so `pnpm
--filter "...[base]"` reports no affected emitter and `detect-affected`
returns `python: false`. That is why Azure#5009 ran no Python CI.

## Fix

Add `pnpm-workspace.yaml` to `sharedExtra`, so any change to it triggers
every emitter target — the same treatment the `core` submodule pointer
already gets.

The file changes rarely and always affects dependency resolution
repo-wide, so this is deliberately blunt rather than trying to work out
which catalog entry moved.

## Verification

Simulated the Azure#5009 diff locally with `BASE_SHA=origin/main`:

```
Affected targets: {"python":true,"java":true,"typescript":true,"go":true}
```

Plus a unit test in `eng/scripts/detect-affected.test.ts`.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 19d6a84d-f603-41ee-8377-6dfb7e661391

Author: msyyc

eng/scripts/detect-affected.config.json

@@ -1,7 +1,7 @@
 {
   "submodulePath": "core",
   "ignore": ["**/test/**", "**/tests/**", "**/*.test.ts", "**/*.md"],
-  "sharedExtra": [".github/actions/setup/**"],
+  "sharedExtra": [".github/actions/setup/**", "pnpm-workspace.yaml"],
   "targets": {
     "python": {
       "package": "@azure-tools/typespec-python",

eng/scripts/detect-affected.test.ts

@@ -96,6 +96,16 @@ describe("computeAffected", () => {
     expect(computeAffected(NONE, ["core"], CONFIG)).toEqual(ALL_AFFECTED);
   });
 
+  // Azure/typespec-azure#5010: catalog upstreams such as
+  // `@typespec/http-client-python` are not workspace packages, so pnpm reports no
+  // affected package when one is bumped. The root workspace file must trigger
+  // every target on its own.
+  it("pnpm-workspace.yaml change triggers all targets", () => {
+    expect(computeAffected(NONE, ["pnpm-workspace.yaml", "pnpm-lock.yaml"], CONFIG)).toEqual(
+      ALL_AFFECTED,
+    );
+  });
+
   it("unrelated root file change triggers nothing", () => {
     expect(computeAffected(NONE, ["README.md", "package.json"], CONFIG)).toEqual(NONE_AFFECTED);
   });

eng/scripts/detect-affected.ts

@@ -21,6 +21,15 @@ import { pathToFileURL } from "node:url";
 // TO ADD A NEW UPSTREAM LIBRARY (e.g. a new typespec-azure-* package that an
 // emitter depends on): nothing to do — the workspace graph picks it up
 // automatically as soon as the emitter declares the dependency.
+//
+// EXCEPTION — upstreams consumed from npm via the pnpm catalog (e.g.
+// `@typespec/http-client-python`): these are not workspace packages, so the
+// graph cannot see them. Bumping one edits only the root `pnpm-workspace.yaml`,
+// which pnpm attributes to the root package alone, leaving every emitter
+// unaffected (Azure/typespec-azure#5010). `pnpm-workspace.yaml` is therefore in
+// `sharedExtra`: any change to it triggers all targets. It changes rarely and
+// always affects dependency resolution repo-wide, so this is deliberately blunt
+// rather than trying to work out which catalog entry moved.
 // -----------------------------------------------------------------------------
 
 interface Target {
@@ -35,7 +44,7 @@ interface Config {
   submodulePath: string;
   /** Globs whose sole change should NOT trigger anything; passed to pnpm via `--changed-files-ignore-pattern`. */
   ignore: string[];
-  /** Paths that trigger every target (shared CI infrastructure). */
+  /** Paths that trigger every target (shared CI infra + the root pnpm workspace file). */
   sharedExtra: string[];
   targets: Record<string, Target>;
 }
@@ -79,7 +88,8 @@ export function matchesAny(file: string, patterns: string[]): boolean {
  * A target fires on any of three signals: its package is in the pnpm-derived
  * affected set, OR one of the two things the graph cannot see changed — the
  * `core` submodule pointer (which every emitter depends on, so it triggers all
- * targets), or a non-package `extra` CI-infra path.
+ * targets), or an `extra` path outside any package (CI infra, and the root
+ * `pnpm-workspace.yaml` — see the header comment).
  *
  * @param affectedPackages Target package OR any graph-dependent of a meaningfully
  *   changed package (from `pnpm --filter "...[base]"`).