Log call renders the key ID as `%!(EXTRA string=...)` instead of a field

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Summary

A structured-log call passes the key ID as a bare positional argument, so it is
rendered into the message as a formatting artefact instead of a field.

app/upbridge/upbridge.go:98:

ub.log.Info("Key not found in cache, contacting nodeman", keyID)

Observed output:

{"level":"INFO","msg":"Key not found in cache, contacting nodeman%!(EXTRA string=edge-receiver-01.edge.test)"}

The node name ends up glued to the message text, so it cannot be filtered or
indexed as a field, and the %!(EXTRA ...) marker leaks into logs.

Reproduction

mqtt-bridge abe75e1. Run the bridge in up mode with Debug = true and
publish a signed message from a node whose key is not yet cached; the line
appears on the first message from each node.

Expected behaviour

The key ID should be a named attribute, matching the other calls in the package.

Suggested fix

-ub.log.Info("Key not found in cache, contacting nodeman", keyID)
+ub.log.Info("Key not found in cache, contacting nodeman", "key_id", keyID)

Worth a quick grep for other odd-argument logging calls at the same time; go vet does not catch this for slog, but sloglint or staticcheck's
SA1029-adjacent checks can.