fix(chatarchive): correct CI Go version, gate ordering, and EOF comparison

- CI workflow: replace hardcoded go-version '1.25' with go-version-file
  to stay in sync with go.mod (was 1.24.6/1.24.7)
- CI script: move coverage threshold checks before summary JSON write
  so artifacts are not written with "passed" status when thresholds fail
- discover.go: use errors.Is(err, io.EOF) instead of bare == comparison
  per Go best practice for wrapped error chains

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: CodeMonkeyCybersecurity

.github/workflows/chatarchive-quality.yml

@@ -47,7 +47,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: '1.25'
+          go-version-file: 'go.mod'
 
       - name: Set up Node
         uses: actions/setup-node@v4

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "prompts"]
-	path = prompts
+	path = third_party/prompts
 	url = ssh://git@vhost7:9001/cybermonkey/prompts.git

pkg/chatarchive/discover.go

@@ -3,6 +3,7 @@
 package chatarchive
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -274,7 +275,7 @@ func isJSONTranscript(path string) bool {
 
 	buf := make([]byte, jsonValidationBufSize)
 	n, err := f.Read(buf)
-	if err != nil && err != io.EOF {
+	if err != nil && !errors.Is(err, io.EOF) {
 		return false
 	}
 	h := strings.ToLower(string(buf[:n]))

prompts

@@ -39,6 +39,17 @@ go test ./internal/chatarchivecmd/... ./cmd/create ./cmd/backup
 echo "==> E2E smoke tests"
 go test -tags=e2e_smoke ./test/e2e/smoke -run 'TestSmoke_(ChatArchive|BackupChats)' -count=1
 
+check_threshold() {
+  local actual="$1" threshold="$2" label="$3"
+  if awk "BEGIN {exit !($actual < $threshold)}"; then
+    echo "FAIL: $label coverage ${actual}% is below the ${threshold}% floor." >&2
+    exit 1
+  fi
+}
+
+check_threshold "$UNIT_COVERAGE" 70.0 "Unit"
+check_threshold "$COMBINED_COVERAGE" 90.0 "Combined"
+
 SUMMARY="Chat archive verification summary
 Unit coverage: ${UNIT_COVERAGE}%
 Combined unit+integration coverage: ${COMBINED_COVERAGE}%
@@ -63,14 +74,3 @@ cat > "$SUMMARY_JSON_FILE" <<EOF
   }
 }
 EOF
-
-check_threshold() {
-  local actual="$1" threshold="$2" label="$3"
-  if awk "BEGIN {exit !($actual < $threshold)}"; then
-    echo "FAIL: $label coverage ${actual}% is below the ${threshold}% floor." >&2
-    exit 1
-  fi
-}
-
-check_threshold "$UNIT_COVERAGE" 70.0 "Unit"
-check_threshold "$COMBINED_COVERAGE" 90.0 "Combined"