renovate: Add source metadata for @pierre/* packages (#14987)

The `@pierre/diffs` and `@pierre/trees` packages publish no `repository` metadata on npm, so their update PRs contain no source links or release notes. This sets `sourceUrl` and `sourceDirectory` for both packages.

The `@pierre/diffs` releases are tagged as `diffs-v1.2.3`, which the release notes lookup does not match for scoped package names. The `extractVersion` pattern accepts these tags while leaving the plain npm versions unchanged.

Author: Turbo87

.github/renovate.json5

@@ -41,6 +41,19 @@
       matchDepNames: ['@catppuccin/palette', '/^@fontsource\\//', '/^@iconify-json\\//'],
       extends: ['schedule:weekly'],
     },
+    {
+      // The `@pierre/*` packages publish no `repository` metadata.
+      matchPackageNames: ['@pierre/diffs'],
+      sourceUrl: 'https://github.com/pierrecomputer/pierre',
+      sourceDirectory: 'packages/diffs',
+      // Match the `diffs-v1.2.3` release tags while leaving npm versions as-is.
+      extractVersion: '^(?:diffs-)?v?(?<version>.+)$',
+    },
+    {
+      matchPackageNames: ['@pierre/trees'],
+      sourceUrl: 'https://github.com/pierrecomputer/pierre',
+      sourceDirectory: 'packages/trees',
+    },
     {
       // Avoid "Artifact update problem" for pnpm updates when the renovatebot
       // setup does not support the new version yet.