docs: scaffold and align control tower ecosystem role

[pramodbn27]

Summary

• update ecosystem language so Agentic Sidecar is framed as the SUPERVISE layer
• align the Control Tower concept and contributor docs with the new ecosystem wording
• keep the Sidecar functionality description explicit that it spans both supervision and governance

Notes

• branch pushed with git
• this PR contains docs and concept updates only

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Propagate the SUPERVISE rename to every ecosystem summary

Changing the canonical Sidecar role here leaves contradictory public guidance: this document still concludes with “Observe. Govern…” on line 990, while README.md lines 5, 98, and 183 and ROADMAP.md line 95 also continue to label Sidecar as GOVERN. Readers therefore receive different role names depending on the entry point, so update those summaries to SUPERVISE as part of this ecosystem-story change.

AGENTS.md reference: AGENTS.md:L156-L160

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