Count pending work: BGG's export lags, so raw queue rows lie

The card read "1 version updates" while upload said "skipping 1 already
done". Both were right. Recon on the live site shows the update DID
apply — the version cell reads "English first edition Year: 2012" and
its radio is checked — but BGG's XML collection export still reports
that collid with no version, even on a forced refresh. diff reads the
API, so it re-queued finished work; the log correctly refused it.

Nothing to fix in the flow: the pipeline card now counts PENDING jobs
(queue rows minus what the log completed) for both to_add and
to_update, reports outstanding failures rather than every failure ever
logged, and when everything queued is already applied it says so and
names the cause. Documented under "BGG's collection export lags the
site" so the next person doesn't chase it as a bug.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jXZFSTZQKzAC8fqpWSz9g

docs/bgg-upload-flow.md

@@ -167,3 +167,22 @@ cannot say which copy it edits. The collection table can:
 
 This is strictly additive: it sets one field on one collid and cannot
 create a duplicate entry.
+
+### BGG's collection export lags the site
+
+After a successful update the website shows the new version immediately
+(the row's version cell reads e.g. "English first edition Year: 2012",
+and reopening the editor shows that radio checked), but the XML API's
+`/collection` export can still report the entry with no version — even
+with a cache-busting re-request. `diff` reads the API, so it will
+re-queue work that has already landed.
+
+Consequences to keep in mind rather than "fix":
+
+- The upload log is the authority on what this tool did; the API is the
+  authority on what BGG has published. They disagree for a while.
+- `build_queue` skipping a job whose log says done is CORRECT here — the
+  work is applied, and re-running it would be a no-op at best.
+- Anything user-facing should count PENDING jobs (queue rows minus what
+  the log completed), never raw queue rows, or settled work reads as
+  outstanding until the next diff.