docs(k8s-proxy): add Kubernetes Proxy REST API guide

Adds versioned_docs/version-4.0.0/running-keploy/k8s-proxy-api.md, a
full REST API guide for the keploy/k8s-proxy service in the v4 docs.
Mirrors running-keploy/public-api.md: authentication, response format,
quickstart, endpoint reference, and related guides.

Covers the control-plane surface exposed behind a cluster-wide shared
bearer token: recording start/stop/status, replay, reports, schema
coverage, auto-replay config, ATG sandbox routes, /k8s-proxy/* data
routes, and proxy self-update. Calls out the unique benefits versus
running the enterprise CLI directly (zero-touch webhook injection,
one API per Deployment, namespace scoping, durable session/log state,
self-updating image, static dedup at the edge).

Authentication section explains that the token is generated at proxy
Pod startup via crypto/rand, reported to the api-server through the
heartbeat channel, and retrieved by callers via the api-server route
GET /cluster/getApp (or /cluster/getApps). The shared token is not
sourced from a Helm Secret or env var, and it rotates on every Pod
restart, so programmatic callers must re-fetch it before each run.

This commit replaces the earlier draft of this file from the original
PR #838 commits, which described a DaemonSet capture mode and a
RecordingSession custom resource that do not exist in the keploy/
k8s-proxy code, plus a /k8s-proxy/mode route, a /k8s-proxy/apps/ensure
route, and a Helm-based shared-token Secret recipe that the chart does
not provision.

Also adds the page to the v4 API Reference sidebar and extends the
Vale base vocabulary with the domain terms used in the new guide.

Signed-off-by: Asish Kumar <officialasishkumar@gmail.com>

Author: officialasishkumar

vale_styles/config/vocabularies/Base/accept.txt

@@ -106,10 +106,19 @@ shipping_address_id
 [Ll]inux
 [Ee]nv
 [Kk]8s
+IPs
 [Dd]edup
+[Dd]edups
+[Rr]ollout[s]?
+[Pp]refill[s]?
+[Aa]uditable
+[Cc]ooldown
+[Ll]iveness
 [Cc]ron
 [Tt]oolchain
 [Rr]untime[s]?
+MongoIDs
+initialised
 normalisation
 behaviour
 polyglot