Analytics: Environment Filtering — CAEM: accept `environment` at ingest and filter on it in the query API

Summary

CAEM (Content Analytics Event Manager) accepts an optional environment parameter at ingest and honors it as a filter on the three live query endpoints — GET /v1/events, GET /v1/content, GET /v1/sessions — following the exact pattern already used for project. Omitted → today's unfiltered, blended-across-environments behavior, unchanged.

Parent epic: #37349
Spike: #37107
Depends on: the ClickHouse schema sub-task (recreates analytics.events + the 10 downstream tables with environment as a key dimension) — nothing here can write to or filter on a column that doesn't exist yet.

Background

Per ADR-0022 rule 2, both changes below are the safe, directly-shippable case: "new optional query parameter... default must be exactly what the endpoint already did before the parameter existed."

• Ingest (POST /v1/event/ingest): today accepts tenant (from the Bearer token) and project (request param) only. Add environment, threaded the same way project already is: IngestionContext → SaveEventRequest → SaveEventRepository.insertChunk(). Omitted → environment = '' (today's implicit, fully-commingled behavior).
• Query endpoints: EventsAnalyticsController, ContentAnalyticsController, SessionsAnalyticsController each get an optional environment @RequestParam, per the standard controller-validation conventions (.claude/conventions.md) — no @Size, no @Pattern (it's an open string set sourced from infra config, not a fixed enum, same reasoning as why project has no pattern constraint either). Omitted → no filter, preserving compatibility for any caller that hasn't adopted the parameter yet.

No EventAnalyticsProxyHelper (dotCMS-core) change needed for the query side — verified in the spike: it forwards every query parameter from the original request transparently (uriInfo.getQueryParameters().forEach(...)) before appending project= only if absent, and events/sessions/content are already in its ALLOWED_PATH_PREFIXES. Once Angular adds &environment=prod to a call, it reaches CAEM with zero core-proxy code changes. (The ingest side is different — the collector has to be told its own environment value to send it; that's covered by the dotCMS-core sub-task, not this one.)

The older, @Deprecated(forRemoval = true) per-metric controllers get no new work.

Scope

• POST /v1/event/ingest: optional environment request param, same shape/threading as project, through IngestionContext → SaveEventRequest → SaveEventRepository.insertChunk().
• GET /v1/events, GET /v1/content, GET /v1/sessions: optional environment @RequestParam, filtering the underlying QueryDSL predicates against the now-environment-aware tables.
• Update the hand-written QueryDSL Q-types (QContentEventsCounter, QPageviewsByDeviceBrowserDaily, QContentPresentsInConversion, QEngagementDaily, QSessionsByDeviceDaily, QSessionsByBrowserDaily, QSessionsByLanguageDaily) to expose an environment field, mirroring how each already exposes tenant/project — moved here from #37406, which is schema-only (docker/init/*.sql). Matches this codebase's own precedent: the experiment columns added by #37016/#37017 never touched a single Q-type until a query actually needed to filter/select by them; a Q-type gains a field only when the query work that uses it lands, not when the underlying column is created.
• Update the shared predicate builders (QueryPredicateBuilder, EventQueryPredicateBuilder, AttributionQueryPredicateBuilder, AnalyticsQueryPredicateBuilder) and AnalyticsQuery to carry environment alongside tenant/project/siteId.
• Update .claude/conventions.md's controller-parameter table to document environment alongside the existing rows.
• Per .claude/testing.md's Postman maintenance rule: update postman/CAEM-dotCMS-Proxy.postman_collection.json — add environment to relevant POST bodies and GET query strings, plus a negative/empty-environment case.
• Update the IT suites per the existing checklist: EventIngestionControllerIT, EventsAnalyticsControllerIT, ContentAnalyticsControllerIT, SessionsAnalyticsControllerIT (happy path with environment set, omitted-param backward-compat case, cross-environment isolation case).

Out of scope

• EventAnalyticsProxyHelper changes — confirmed unnecessary (see Background).
• The deprecated per-metric controllers.
• Authorization for cross-environment reads — explicitly deferred by the epic; CAEM auth stays tenant-scoped, nothing here restricts which environments a valid Bearer token can query.
• ClickHouse schema/table changes (previous sub-task, #37406) — the column and its ORDER BY/PARTITION BY position are already defined there; this ticket only adds the Java-side Q-type fields and query-layer support.

Dependencies

Blocked on the ClickHouse schema sub-task landing first. The dotCMS-core sub-task (collector plumbing) and this sub-task can proceed in parallel — an unrecognized request param is silently ignored by Spring MVC, and an omitted param defaults safely on both sides, so there's no required ordering between "collector sends &environment=" and "CAEM reads it."

Acceptance Criteria

• Ingesting an event with environment set persists it correctly on analytics.events; omitting it persists '' (unchanged from today)
• All three query endpoints accept optional environment and return only that environment's data when set
• All 7 Q-types (QContentEventsCounter, QPageviewsByDeviceBrowserDaily, QContentPresentsInConversion, QEngagementDaily, QSessionsByDeviceDaily, QSessionsByBrowserDaily, QSessionsByLanguageDaily) expose environment and compile
• Omitting environment on any query endpoint reproduces today's unfiltered behavior exactly (epic acceptance criterion)
• Cross-environment isolation verified end-to-end (ingest into two environments for the same tenant/project, query one, confirm the other's rows are excluded)
• Postman collection updated per .claude/testing.md's maintenance rule
• All new/changed IT classes pass under mvn verify

Next step

Run /speckit-specify against this issue to produce the formal spec before implementation.