Assess `improve-codebase-architecture` usefulness on Argos

[bracyw]

Follow-up from the Matt Pocock skills adoption PR (#646).

Run improve-codebase-architecture against Argos and judge whether its suggestions are actually useful to developers.

Acceptance

• Run the skill against angular-client and scylla-server.
• Capture which suggestions were actionable vs. noise.
• Refine the CONTEXT.md / docs/adr/ inputs the skill relies on if weak inputs caused weak suggestions.

Tooling-evaluation follow-up; not blocking.