fix(deploy): r2 getJSON must not read transient API errors as missing objects

A CF API 502 on the manifest.json probe made publish-libs misdetect an
already-published tag as unpublished and start a full republish (byte-identical
immutable content, so harmless — but ~30 min of redundant uploads before a
second 502 killed it). Only wrangler's definitive missing-object error now
reads as absent; anything else throws.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011CC8aAnUUHcnHy3QCJtUwb

scripts/deploy/lib/cdn-store.mjs

@@ -135,8 +135,17 @@ export function r2Driver({ bucket, remote }) {
         run(["r2", "object", "get", `${bucket}/${key}`, "--file", dest, ...flags], {
           quiet: true,
         });
-      } catch {
+      } catch (e) {
-        return null; // not found / error → absent (expected on first publish)
+        // ONLY a definitive "no such object" reads as absent. Any other failure
+        // (CF API 5xx, auth, network) must THROW: publishers branch on these
+        // probes — publish-libs once misread a transient 502 on manifest.json
+        // as "tag not published" and started a full republish of an existing
+        // immutable tag (harmless bytes-wise, ~30 min wasted).
+        const msg = `${e?.stderr ?? ""}${e?.stdout ?? ""}${e?.message ?? ""}`;
+        if (/does not exist|no such object|not found|404/i.test(msg)) return null;
+        throw new Error(
+          `r2 get ${bucket}/${key} failed (NOT a missing-object miss): ${msg.slice(0, 400)}`,
+        );
       }
       try {
         return JSON.parse(readFileSync(dest, "utf8"));