Add telemetry ingest, feedback collector, pressure API and insight CLI

Completes FLUID-WP-0005. Normalization and redaction live on one path,
shared by the in-process emitter and the ingest endpoint: two paths with
two normalizations would eventually disagree, and the disagreement would
surface as a pressure finding that is really a pipeline bug.

Telemetry kind is inferred from event shape rather than defaulting to
"request", since an error filed as a request understates the interface's
failure rate. A malformed event in a batch does not discard the rest.

Feedback is stored as evidence and creates no pressure and no hypothesis
on its own, per API Standards 15, with the consumer recorded as the
actor so their untrusted status stays visible in the audit trail. The
feedback endpoint is the only consumer-reachable part of the control
plane.

The observation endpoints are not served at all when no pseudonymization
salt is configured, rather than served with a generated one: a salt that
changed per run would make the same consumer look new every time and
every cohort count wrong.

Adds an end-to-end test driving real traffic through the gateway and
confirming it becomes a classified pressure record, with no raw consumer
identity reaching the store.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014KmVxhJ35tCo7rE7UnLwWu

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1116572@bnt-lap001
Assistant-Session: 8ba9bb93-a72a-4883-b189-2499cce5c400

cmd/fluid/main.go

@@ -30,6 +30,11 @@ Commands:
   revision show    Show one revision descriptor
   policy put       Install a routing policy
   policy show      Show the current routing policy
+  pressure list    List recorded interface pressure
+  pressure analyze Classify recent telemetry into pressure records
+  pressure dismiss Record that a pressure will not be acted on
+  cohort           Summarize cohort populations
+  fitness compare  Compare a candidate revision against its control
   events           Show audit events
   telemetry        Show recorded telemetry
   audit trace      Reconstruct the history behind a revision
@@ -113,6 +118,12 @@ func run(args []string) error {
 		return runEvents(ctx, g, rest)
 	case "telemetry":
 		return runTelemetry(ctx, g, rest)
+	case "pressure":
+		return runPressure(ctx, g, rest)
+	case "cohort":
+		return runCohort(ctx, g, rest)
+	case "fitness":
+		return runFitness(ctx, g, rest)
 	case "audit":
 		return runAudit(ctx, g, rest)
 	default: