story: Toggle Platform Mesh components at runtime (enable/disable)

[Perseus985]

User Story

As a Platform Mesh operator,
I want to enable and disable components in a running instance (via Helm values),
so that I can adapt a stack's footprint and capabilities on demand without redeploying or rebuilding it.

Acceptance Criteria

• Components can be enabled and disabled via Helm values on an already-running installation.
• Enabling or disabling an optional component does not require a redeploy of the stack and does not disrupt the Core components (kcp, platform-mesh-operator, security-operator, account-operator stay healthy).
• Disabling a component removes its workloads and frees the associated resources (pods, services, ingress).
• Re-enabling a component restores full functionality, and existing resources remain intact and are reconciled correctly (no recreation or data loss).
• Dependency constraints are respected — a component cannot be enabled without its prerequisites, and a warning/error is raised on invalid combinations.
• The set of toggleable components and their dependencies is documented.
•  Core components cannot be disabled (always-required guarantee enforced).

Parent Epic

#290

Additional Context

Across the Opendefense Cloud, stacks exist in different sizes (data center, deployable/field, mobile) and a stack may move between environments, scale up or down, or shift its mission profile, which changes what capabilities it needs.

Rather than maintaining separate builds per size or rebuilding when requirements shift, operators must be able to compose a stack at runtime — turning optional components (e.g. the Portal/OpenMFP) on or off as needed — while the always-required Core remains stable. This keeps the uniform "manage all stacks the same way" operating model intact regardless of footprint.