fix(cd): compute the first fork RC without a tag that does not exist

The first CD run after the release work merged failed:

  Latest release: fork-v0.0.0
  fatal: ambiguous argument 'fork-v0.0.0..HEAD': unknown revision

With no fork-v tag yet, the job synthesised "fork-v0.0.0" as a starting point for
the version arithmetic and then fed that same string to git log as a ref. It is
not one. Every RC would have failed until the first stable release existed —
which itself requires a working release path.

Separates the two concerns: 0.0.0 is the version baseline, and the commit range
is all of history when there is no tag to start from.

The prior isolated test of this logic passed because it only exercised the
version maths, never the git log that consumes its output. Verified this time by
running the real branch logic against the real repository:

  kylehgc/rtk: base=0.0.0  range=HEAD           -> fork-dev-0.1.0-rc.N
  rtk-ai/rtk:  base=0.44.1 range=v0.44.1..HEAD  -> dev-0.45.0-rc.N

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: kylehgc

.github/workflows/cd.yml

@@ -93,19 +93,24 @@ jobs:
           # Exclude pre-release tags. Match on '-rc' rather than any '-', because the
           # fork prefix itself contains a hyphen.
           LATEST_TAG=$(git tag -l "$TAG_GLOB" --sort=-version:refname | grep -v -- '-rc' | head -1)
-          if [ -z "$LATEST_TAG" ]; then
-            if [ -n "$TAG_PREFIX" ]; then
-              LATEST_TAG="${TAG_PREFIX}v0.0.0"   # fork has not cut a stable release yet
-            else
-              echo "::error::No stable release tag found"
-              exit 1
-            fi
+          if [ -n "$LATEST_TAG" ]; then
+            LATEST_VERSION="${LATEST_TAG#${TAG_PREFIX}v}"
+            COMMIT_RANGE="${LATEST_TAG}..HEAD"
+            echo "Latest release: $LATEST_TAG"
+          elif [ -n "$TAG_PREFIX" ]; then
+            # The fork has not cut a stable release yet. 0.0.0 is a starting point for
+            # the version maths, NOT a ref — `git log 0.0.0..HEAD` would abort — so the
+            # range has to be all of history.
+            LATEST_VERSION="0.0.0"
+            COMMIT_RANGE="HEAD"
+            echo "No ${TAG_PREFIX}v tag yet; starting the fork's version line at 0.0.0"
+          else
+            echo "::error::No stable release tag found"
+            exit 1
           fi
-          LATEST_VERSION="${LATEST_TAG#${TAG_PREFIX}v}"
-          echo "Latest release: $LATEST_TAG"
 
           # ── Analyse conventional commits since that tag ──
-          COMMITS=$(git log "${LATEST_TAG}..HEAD" --format="%s")
+          COMMITS=$(git log $COMMIT_RANGE --format="%s")
           HAS_BREAKING=$(echo "$COMMITS" | grep -cE '^[a-z]+(\(.+\))?!:' || true)
           HAS_FEAT=$(echo "$COMMITS"    | grep -cE '^feat(\(.+\))?:'     || true)
           HAS_FIX=$(echo "$COMMITS"     | grep -cE '^fix(\(.+\))?:'      || true)