Issue #3593894: pdv_eca submodule — ECA event plugin for PdvAuditableEvent
Adds the optional pdv_eca submodule, which surfaces PdvAuditableEvent to ECA so operators can react to vault activity without writing code.
A single ECA event plugin covers all pdv channels and actions. Site builders filter by channel (e.g. pdv.dormancy) and action (e.g. warned) in the model configuration form, or leave either blank to match everything. The plugin exposes tokens: [event:channel], [event:action], [event:owner_uid], [event:tenant], [event:resource], [event:deadline].
No services.yml needed: ECA discovers the plugin via PSR-4 and the #[EcaEvent] attribute.