DEFAULT_CONFIG ships a root-level `personalities: {}` (from #643) and the schema
whitelists it, but the single personality resolver read only
`agent.personalities`. A user who followed the generated config saw
"No personalities configured" from /personality on CLI, gateway and TUI.
`available_personalities()` now merges root `personalities` then
`agent.personalities` (later wins), so all three consumers pick both up.
Earlier attempt: PR #9657 (@flobo3) patched the CLI loader only.
Fixes#9636
44ce128a27