docs: align FlowALP naming in architecture and readme

[liobrasil]

Closes: #???

Description

Revives the useful docs-only part of #169 on top of current main.

• replace stale Flow Credit Market (FCM) references with FlowALP in RebalanceArchitecture.md
• align README.md wording so FlowALPv0 is described as the current Cadence implementation
• fix the bundled supervisor name to FlowALPSupervisorv1
• add a brief implementation note clarifying the current pool type

No tests run; docs-only change.

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