Buzz Desktop v0.4.21

• fix(desktop): clarify data deletion action (#2208) (e315c498)
• feat: brand authentication complete page (#2192) (1470ac3a)
• fix(buzz-acp,buzz-agent): surface stall duration and fate (#2204) (cd6b573f)
• fix(desktop): resolve activity feed showing channel UUID instead of message content (#2201) (c5d00a35)
• feat(cli): add agents archive/unarchive/archived subcommands (#2173) (7d799206)
• Simplify first-community onboarding choices (UI only) (#2194) (6ab45d75)
• Fix persisted agent defaults display (#2182) (d538111b)
• fix(timeout): unified turn-timeout fix — cap inheritance, steer renewal, activity-aware requeue, LLM stall surfacing (#2175) (0f86a608)
• fix(desktop): scope draft store per workspace relay (#2179) (2eff2cb3)
• fix(desktop): avoid forwarding click event as channel callback (#2174) (9ed843a0)
• Polish agent defaults surfaces: app dropdowns + collapsed Advanced env vars (#2184) (8c77a0cf)