Add config option to opt out of automatic /v2 suffix on CAMUNDA_REST_ADDRESS

Summary

Please add a configuration option to opt out of the automatic /v2 suffix that the SDK appends to CAMUNDA_REST_ADDRESS (e.g. an env var CAMUNDA_REST_ADDRESS_EXACT=true and/or a config field CAMUNDA_REST_ADDRESS_EXACT).

Current behaviour

_normalize_rest_address() unconditionally appends /v2 unless the value already ends in /v2 (in runtime/configuration_resolver.py):

@staticmethod
def _normalize_rest_address(value: str) -> str:
    value = value.strip()
    if not value:
        return value
    normalized = value.rstrip("/")
    if normalized.endswith("/v2"):
        return normalized
    return normalized + "/v2"

This runs in the @model_validator(mode="after") on CamundaSdkConfiguration, normalizing both CAMUNDA_REST_ADDRESS and ZEEBE_REST_ADDRESS. The field doc even states "/v2 is appended automatically if missing" — there is no way to have the SDK use the address exactly as provided.

Why this is a problem

For deployments behind an API gateway / reverse proxy, the effective base path often does not follow the .../v2 convention (the gateway may mount the REST API under a different prefix, or strip/rewrite path segments). Because the suffix is unconditional, these setups cannot be expressed through configuration alone.

Impact / current workaround

We consume this family of SDKs in camunda/c8ctl and support gateway-fronted profiles via c8ctl add profile --exactBaseUrl. To make that work with SDKs that force the /v2 suffix, we have to rewrite outgoing request URLs to strip the SDK-computed .../v2 and substitute the profile's literal base URL. This is brittle and couples us to the SDK's internal URL format.

Proposed solution

Add a boolean config/env option — e.g. CAMUNDA_REST_ADDRESS_EXACT=true — that short-circuits _normalize_rest_address() so the configured address is used verbatim (no /v2 appended).

Alternatives considered

• Requiring users to embed /v2 in the address — doesn't help, since the gateway path may differ from the /v2 convention entirely.
• URL rewriting in a custom transport (our current workaround) — works but is fragile.

Cross-SDK note

This is a family-wide behaviour: the JS, Go, C# and Rust SDKs all append /v2 unconditionally with no opt-out. Tracking issue on the JS SDK: camunda/orchestration-cluster-api-js#499. It would be ideal to align the opt-out mechanism (env var name + config field) across all five SDKs.

Start in runtime/configuration_resolver.py with _normalize_rest_address() and the CamundaSdkConfiguration model validator, then trace how CAMUNDA_REST_ADDRESS and ZEEBE_REST_ADDRESS are loaded. Add the proposed exact-address configuration behavior and verify that both addresses can bypass automatic /v2 appending while retaining current normalization by default.