feat(discord): release -> #announcements auto-post + pin + GitHub Discussions (#2201)

On a published GitHub release, post the notes to the ECC Discord
#announcements channel (via bot), pin it, and cross-post to GitHub
Discussions (Announcements category). Release data flows through env vars
(no shell interpolation of untrusted input). Secrets: DISCORD_BOT_TOKEN,
DISCORD_ANNOUNCE_CHANNEL_ID (repo secrets), GITHUB_TOKEN.

Ties the 2.0.0/1.11.0 official release to the community launch.

Co-authored-by: ECC Test <ecc@example.test>

.github/workflows/release-announce.yml

@@ -0,0 +1,27 @@
+name: Release Announce
+
+on:
+  release:
+    types: [published]
+
+permissions:
+  contents: read
+  discussions: write
+
+jobs:
+  announce:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+      - name: Announce release to Discord + Discussions
+        run: node scripts/discord/release-announce.mjs
+        env:
+          DISCORD_BOT_TOKEN: ${{ secrets.DISCORD_BOT_TOKEN }}
+          DISCORD_ANNOUNCE_CHANNEL_ID: ${{ secrets.DISCORD_ANNOUNCE_CHANNEL_ID }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_REPOSITORY: ${{ github.repository }}
+          RELEASE_NAME: ${{ github.event.release.name }}
+          RELEASE_TAG: ${{ github.event.release.tag_name }}
+          RELEASE_URL: ${{ github.event.release.html_url }}
+          RELEASE_BODY: ${{ github.event.release.body }}