docs: query comments say what each query selects and why, not how it came to be (#6277)

Rewrites the internal/db/queries comments to rule 32 and regenerates
dbq, whose doc comments and embedded SQL carry them. The bugs behind the
tiered mixes, the md5 order seed, the score bands and the round-robin
arms are restated as the constraint each one enforces; counts from one
library and stale cross-references are gone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/queries/admin_summary.sql

@@ -1,14 +1,14 @@
 -- name: AdminSummary :one
--- What the admin rail and the Overview's verdict read (#5605): each queue
+-- What the admin rail and the Overview's verdict read: each queue
 -- that waits on a person, with how many and since when. One round trip, so
 -- the rail costs one cheap read on every admin page. The "since" is the
 -- oldest item still waiting: how long the queue has been left, which is what
--- tells the operator a count of 2 is fine today and wrong after a month.
+-- tells an admin a count of 2 is fine today and wrong after a month.
 SELECT
     (SELECT count(*) FROM requests WHERE status = 'pending')::bigint                AS requests,
     (SELECT min(requested_at) FROM requests WHERE status = 'pending')::timestamptz  AS requests_since,
     -- A broken track is one report however it was found: a listener flagged
-    -- it, or it failed to play (#5606). Counted by track, as the Reports
+    -- it, or it failed to play. Counted by track, as the Reports
     -- page lists them.
     (SELECT count(*) FROM (
         SELECT track_id FROM quarantine