feat: add token support for kubectl commands

[EItanya]

Some users of the kagent tool server want to be able to use client authentication for k8s tools. In order to enable this, the k8s tools will now attempt to pass Bearer tokens from the request into the kubectl commands.

Introduces helm values for configuring this:

# When true: pods use the default service account and no ClusterRole/ClusterRoleBinding are created.
# When false: a dedicated ServiceAccount and RBAC are created.
UseDefaultServiceAccount: false

tools:
  k8s:
    # When true: a Bearer token in the Authorization header on each request is passed to kubectl; fails if missing
    # When false: kubectl uses in-cluster ServiceAccount.
    tokenPassthrough: false

Testing

Defaults (matches current approach)

UseDefaultServiceAccount: false
tools:
  k8s:
    tokenPassthrough: false

Output:

time=2026-02-16T19:56:35.920Z level=INFO msg="executing command" trace_id=bd2fb0c590239cb8b183e60f4c0801bd span_id=7dcc9f5c919cb145 command=kubectl args="[get namespaces -o wide]"
time=2026-02-16T19:56:36.153Z level=INFO msg="command execution successful" trace_id=bd2fb0c590239cb8b183e60f4c0801bd span_id=7dcc9f5c919cb145 command=kubectl args="[get namespaces -o wide]" duration=0.233024001

Token passthrough + disable service account

UseDefaultServiceAccount: false
tools: 
  k8s:
    tokenPassthrough: false

With token:

time=2026-02-16T19:59:41.010Z level=INFO msg="executing command" trace_id=bd2fb0c590239cb8b183e60f4c0801bd span_id=ce0a811d4704fc88 command=kubectl args="[get namespaces -o wide --token <REDACTED>]"
time=2026-02-16T19:59:41.384Z level=INFO msg="command execution successful" trace_id=bd2fb0c590239cb8b183e60f4c0801bd span_id=ce0a811d4704fc88 command=kubectl args="[get namespaces -o wide --token <REDACTED>]" duration=0.374007129

Without token, the client receives:
Bearer token required when TOKEN_PASSTHROUGH is true

[dimetron]

@EItanya I have only concern if this will be consistent across all other tools

[EItanya]

@EItanya I have only concern if this will be consistent across all other tools

I think that's fair, the issue is that not all CLIs allow for passing tokens in this way