feat(audit-logs): paging + filters + outcome/ip/userAgent + field rename

[jlc488]

Second PR in the admin-ui ↔ backend contract-gap series (after #14). The admin UI's Audit Logs page sends rich query parameters and expects a Spring Data Page shape; this controller only had a flat tenantId + since lookup.

Summary

Schema (V9)

• Three nullable columns on platform_audit_log:
  • outcome VARCHAR(16) — SUCCESS / FAILURE. NULL on legacy rows (the response layer treats NULL as SUCCESS).
  • ip_address VARCHAR(64) — actor's network address.
  • user_agent VARCHAR(512) — actor's browser / client.
• Index on outcome (cheap, helps the most common UI filter).
• Existing rows unaffected.

Entity / write path

• PlatformAuditLogEntity gains the three fields and an extended all-args constructor.
• AuditLogService.record reads outcome / ip / userAgent from the AuditEvent metadata map if the publisher stuffs them in. The AuditEvent record itself doesn't carry them as first-class fields yet — that lives in a follow-up so this PR stays focused on the wire shape.

Search

• JpaPlatformAuditLogRepository now extends JpaSpecificationExecutor.
• AuditLogQueryService.search(AuditLogSearchCriteria, Pageable) builds a Specification covering: tenantId, actorLogin (case-insensitive contains on actor_display_name), action, targetType, outcome, from, to. Every filter is optional — null means "any". Default sort: occurredAt DESC.

Wire shape

• AuditLogResponse rewritten to match the admin UI's AuditLog interface: id, tenantId, actorId, actorLogin, action, targetType, targetId, outcome, ip, userAgent, payload, occurredAt. Payload parsed from metadataJson via ObjectMapper; a corrupt blob is surfaced under {"raw": <text>} so a single bad row doesn't sink the page.

Controller

• GET /admin/api/v1/audit-logs is now paginated + filterable. Query params: tenantId, actorLogin, action, targetType, outcome, from, to, page, size. Size capped at 200, default 25, page is 0-based. Response is the standard Spring Page<AuditLogResponse> shape the UI already expects (content, totalElements, totalPages, number, size).
• /audit-logs/user/{userId} preserved as a flat convenience read for the diagnostics drill-down.

Test plan

• ./gradlew build green (55 tasks, all sample-app + audit-core tests pass)
• Wire the admin-ui Audit Logs page against this and exercise date-range filter, outcome filter, paging
• Follow-up: promote outcome / ip / userAgent to first-class fields on AuditEvent so publishers don't have to use the metadata map

What's next in this series

Remaining gaps: Policies (PolicyDescriptor list + nested test body), Tenants (status enum + createdAt + status endpoint), Diagnostics + Settings field rename.