fix(#355 review E1=B + F1-F8): gate client telemetry OFF by default + throttler/lifecycle/overflow fixes

Maintainer resolved E1 as variant B: the public vitals sink + client collection
must be OFF by default (else client_metrics grows unbounded on a self-host deploy
with no external pruner, via an unauthenticated public endpoint).

- F1: new operator flag CLIENT_TELEMETRY_ENABLED (default OFF), SEPARATE from
  METRICS_PORT (Grafana reads the table directly, independent of the scrape port).
  ClientTelemetryModule.register() provides VitalsController ONLY when the flag is
  true (route absent otherwise); the flag reaches the client via window.CONFIG
  (config.ts isClientTelemetryEnabled), and initVitals() early-returns when off.
- F2/F3 [throttler]: this repo's ThrottlerGuard applies EVERY named throttler to
  every guarded route unless skipped. The new VITALS bucket therefore (a) newly
  bound collab-token → 429 behind shared/NAT IPs, and (b) the vitals route didn't
  skip the stricter public-share-ai (5/min) bucket → effective 5/min not 120.
  Fix (additive, global config unchanged): vitals.controller @SkipThrottle the
  other buckets + @Throttle VITALS 120/min; collab-token adds VITALS_THROTTLER to
  its existing @SkipThrottle (restoring its prior effectively-unthrottled state).
- F4: metrics node:http server is closed on shutdown (MetricsServerLifecycle
  OnModuleDestroy → closeMetricsServer(), fired by enableShutdownHooks).
- F5: docSize outside [0, int4-max] drops to null (keeping the event) instead of
  overflowing int4 and failing the WHOLE batch insert (+ 2 tests).
- F6: .env.example documents METRICS_PORT (no default — unset = subsystem OFF) +
  CLIENT_TELEMETRY_ENABLED; fixed the inaccurate "default 9464" wording.
- F7: disabled/non-sampled sessions install ZERO observers — isVitalsActive()
  (enabled && sampled) gates reportClientMetric AND the page-editor
  measurePageOpen + dispatchTransaction wrapping.
- F8: kept db.d.ts hand-added (wontfix) — this repo HAND-CURATES db.d.ts (verified
  across recent fork migrations a32fba63/8c5b57eb/fdeede00); codegen would be the
  deviation. The ClientMetrics interface maps the migration 1:1.

Gate: server tsc 0, client tsc 0, server metrics/vitals/telemetry/throttle 21
tests, client route-template 5. No new deps.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/server/src/core/telemetry/vitals.controller.ts

@@ -6,10 +6,16 @@ import {
   Req,
   UseGuards,
 } from '@nestjs/common';
-import { Throttle, ThrottlerGuard } from '@nestjs/throttler';
+import { SkipThrottle, Throttle, ThrottlerGuard } from '@nestjs/throttler';
 import { FastifyRequest } from 'fastify';
 import { Public } from '../../common/decorators/public.decorator';
-import { VITALS_THROTTLER } from '../../integrations/throttle/throttler-names';
+import {
+  AI_CHAT_THROTTLER,
+  AUTH_THROTTLER,
+  PAGE_TEMPLATE_THROTTLER,
+  PUBLIC_SHARE_AI_THROTTLER,
+  VITALS_THROTTLER,
+} from '../../integrations/throttle/throttler-names';
 import { VitalsService } from './vitals.service';
 
 /**
@@ -25,6 +31,17 @@ export class VitalsController {
 
   @Public()
   @UseGuards(ThrottlerGuard)
+  // The global ThrottlerGuard applies ALL named throttlers to every route, so
+  // every OTHER bucket must be skipped here — otherwise the strictest of them
+  // (public-share AI at 5/min) would override the intended vitals limit and cap
+  // this route at 5/min instead of 120/min. Skip them all so ONLY the VITALS
+  // bucket below applies.
+  @SkipThrottle({
+    [AUTH_THROTTLER]: true,
+    [AI_CHAT_THROTTLER]: true,
+    [PAGE_TEMPLATE_THROTTLER]: true,
+    [PUBLIC_SHARE_AI_THROTTLER]: true,
+  })
   @Throttle({ [VITALS_THROTTLER]: { limit: 120, ttl: 60_000 } })
   @Post('vitals')
   @HttpCode(200)