Extract kotlin-spring-commons (modular) + reconcile + personal-stack adopt

[jorisjonkers-dev-agents]

Objective: publish modular Maven artifacts (command, events, blocks, web, exceptions, vault, vault-jwt, observability, timing-web, timing-jooq, crac, email, archunit-test). Largest dedup win.

Notes: reconcile website's diverged vault + typed CommandBus before fixing APIs; messaging deferred (hardcodes personal-stack.events/queue names); each Spring add-on owns its AutoConfiguration.imports; Dockerfiles stop copying workspace libs and resolve packages in build stages.

Work:

• Split kotlin-common into modules + publish
• personal-stack services depend on pinned artifacts per module
• Account for the two CommandBusConfig copies + 3 direct result-handler call sites

Part of #605.