Document AuditTrail::event() chain resolution and the default-chain catch-all (fix the dblog wording)

The chain-routing docs cover the PSR-3 logger path (mode flag/auto, channels[], chain: TRUE) well, but they do not document how AuditTrailInterface::event() selects its chain - a separate path with different rules. The result is real operator confusion: rows land in the default chain even though it has an empty channels list and mode: flag.

The behaviour

• AuditTrail::event() resolves its chain as: a chain whose id equals the channel, else a chain that lists the channel in channels[], else the default chain (see AuditTrail::resolveChain()). It then records the row unconditionally - the chain's mode does NOT gate event(); mode only gates the PSR-3 logger path.
• So the default chain is the universal catch-all for every event() write (and every chain: TRUE logger call) whose channel no chain claims - regardless of the default chain's mode or channels.

What the docs get wrong / omit

• consumers.md - "Orchestrator path: event()", step 1 only says "Resolves the active chain for the channel". It omits the resolution order and the records-regardless-of-mode rule.
• configuration.md - the channels[] section says unmapped-channel entries flow through to whatever chain claims that channel next, or to plain dblog if none does. For event() (and chain: TRUE logger calls) that is incorrect: they land in default, not dblog.
• The default chain's role as the catch-all is not stated on the configuration page or the chain edit form, so an operator reasonably expects an empty-channels / flag-mode chain to receive nothing.

Proposed changes

• consumers.md: document the event() chain-resolution order (channel-as-id, then channels[], then default fallback) and that event() records regardless of mode.
• configuration.md: correct the dblog wording to state that unmapped event() / chain: TRUE writes fall back to the default chain, and describe default as the catch-all.
• Chain edit form: add a one-line note that the default chain catches unmapped channels regardless of mode.