news-digest: fixes from first deploy on ana-docker

Three iterations to get end-to-end:

1. Dockerfile missed COPY run-digest.sh — cron's exec target wasn't
   in the image, every fire failed. Added COPY + chmod.

2. Jinja template used {{ list|sum(attribute='items') }} which
   sum()s lists with start=0 → TypeError int+list. Switched to
   computing reddit_total / tech_total in Python and passing as
   template args.

3. LLM defaulted to qwen3.5-35-a3b which (a) is broken in
   llama-swap (model process exits on launch), (b) when working,
   defaults to extended-thinking mode that eats the entire token
   budget without producing any visible content. Same pattern with
   qwen3.6-35-a3b. Switched default to granite-4-small — small (4B),
   fast (~1s/call), no thinking-mode pathology, returns clean JSON.
   Whole pipeline now runs in ~35s total across 8 sources.

Also hardened the LLM response parser to fall back to
reasoning_content when content is empty — catches the thinking-mode
case if anyone ever points the digest at one of those models. Plus
the deploy playbook gained DOCKER_BUILDKIT=0 because ana-docker is
on docker 20.10 which doesn't carry the buildx driver versions our
newer client expects ("client version 1.52 is too new"). Real fix is
upgrading docker on the fleet — separate workstream.

stacks/news-digest/digest.py

@@ -275,7 +275,11 @@ def summarize_source(src: Source) -> None:
             timeout=LLAMA_SWAP_TIMEOUT,
         )
         r.raise_for_status()
-        content = r.json()["choices"][0]["message"]["content"].strip()
+        msg = r.json()["choices"][0]["message"]
+        # Models in extended-thinking mode (e.g. Qwen3.x defaults) put
+        # output in reasoning_content and leave content empty until they
+        # exit thinking — fall back so we get *something* to parse.
+        content = (msg.get("content") or msg.get("reasoning_content") or "").strip()
         # Some models wrap JSON in ```...``` even when told not to.
         content = re.sub(r"^```(?:json)?\s*|\s*```$", "", content, flags=re.M).strip()
         mapped = {x.get("id"): x for x in json.loads(content)}
@@ -306,9 +310,13 @@ def render(reddit_sources: list[Source], tech_sources: list[Source],
     env.filters["domain"] = _domain
     template = env.get_template("digest.html.j2")
     edition = "morning" if generated_at.hour < 14 else "evening"
+    reddit_kept = [s for s in reddit_sources if s.items]
+    tech_kept   = [s for s in tech_sources if s.items]
     return template.render(
-        reddit_sources=[s for s in reddit_sources if s.items],
-        tech_sources=[s for s in tech_sources if s.items],
+        reddit_sources=reddit_kept,
+        tech_sources=tech_kept,
+        reddit_total=sum(len(s.items) for s in reddit_kept),
+        tech_total=sum(len(s.items) for s in tech_kept),
         generated_at=generated_at,
         edition=edition,
         edition_short="AM" if edition == "morning" else "PM",