Revert 0.3.24 commits off main for clean 0.3.23 cut

[TheGreatAxios]

Three 0.3.24 commits landed on main mid-0.3.23-cut and must leave the release clean. This PR reverts them as three standard revert commits (newest first), with no other changes.

Reverted:

• Restore Gaasbot CTO voice from the GaaS original, keep it off #932 — Restore Gaasbot CTO voice from the GaaS original (revert f173b7e)
• Restore Greybeard review checklist in Corbits idiom #944 — Restore Greybeard review checklist in Corbits idiom (revert 509c1d2)
• Warn when an agent plugin prompt file is missing #928 — Warn when an agent plugin prompt file is missing (revert 94aebf3)

Verification: tree at HEAD is identical to the pre-merge state (9ff51db^) — git diff 9ff51db6^ HEAD is empty. bun run typecheck (exit 0), bun run build (exit 0), and the three reverted packages' tests (43 pass, 0 fail) are green. bun run check is green modulo the known pre-existing oxfmt red on untouched src/subagent/spawn-agent-worktree.test.ts.

Re-merge these three commits after the 0.3.23 tag. DO NOT MERGE this PR here — the parent merges after CI is green.

[linear-code]

Issue reopened: CL-5351 Clean up IIFEs, swallowed catches, and unnecessary React hooks

[TheGreatAxios]

Superseded: Path B won — the three commits stay on main and shipped in 0.3.23 with notes instead. No revert needed.