ci(v1): auto-label [v1] proposals so fork/CLI filings reach the board (#146)

The issue form only applies labels for web-form submissions; contributors
filing via API/CLI or from a fork lack the triage/write needed to set
labels, so their proposals landed unlabeled and never auto-added to the
Silo v1 project. Add an issues:opened workflow that stamps v1-proposed on
any [v1]-titled issue via the repo GITHUB_TOKEN, regardless of filer
permission.

Also drop epic from the proposal template's auto-labels: a fresh proposal
is a candidate, not yet a tracked epic. epic-ness (better: the Epic issue
type) is applied at acceptance/lock alongside v1 + milestone.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/v1-proposal-labeler.yml

@@ -0,0 +1,26 @@
+name: v1 proposal labeler
+
+# The issue form applies `v1-proposed` automatically, but only for submissions
+# through the web form. Contributors filing via the API/CLI (or from a fork)
+# cannot apply labels without triage/write access, so their proposals would land
+# unlabeled and never auto-add to the Silo v1 project. This stamps `v1-proposed`
+# on any issue whose title starts with `[v1]`, regardless of who filed it.
+
+on:
+  issues:
+    types: [opened]
+
+permissions:
+  issues: write
+
+jobs:
+  label:
+    if: startsWith(github.event.issue.title, '[v1]')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Apply v1-proposed
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ISSUE_NUMBER: ${{ github.event.issue.number }}
+          REPO: ${{ github.repository }}
+        run: gh issue edit "$ISSUE_NUMBER" --repo "$REPO" --add-label v1-proposed