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/dbq/lifecycle.sql.go

@@ -22,7 +22,7 @@ type CountGoneGrabsParams struct {
 }
 
 // How many of a release's grabs ended gone since a time: a release that keeps
-// leaving its client is held back rather than taken on every pass (#6176).
+// leaving its client is held back rather than taken on every pass.
 func (q *Queries) CountGoneGrabs(ctx context.Context, arg CountGoneGrabsParams) (int64, error) {
 	row := q.db.QueryRow(ctx, countGoneGrabs, arg.InfoHash, arg.Since)
 	var count int64
@@ -289,7 +289,7 @@ type RaiseInterventionParams struct {
 	Detail   string
 }
 
-// The download lifecycle (M502 #5523): the intervention ledger, giving a
+// The download lifecycle: the intervention ledger, giving a
 // download up, and seeding after import.
 // A condition seen, or seen again: a second pass lands on the open row, so
 // a download stuck for a week is one row that says how long. The name only