show owner badges for duplicate-named agents

[tellaho]

Category: new-feature
User Impact: When multiple agents in a room share the same name, users can tell them apart by the owning user's avatar shown inline next to the agent name.
Problem: Duplicate-named agents currently appear identical in the message timeline, which makes it hard to know which human owns or configured each agent. The first implementation reserved the inline badge space but could render a blank fallback during cold loads.
Solution: Detect duplicate agent names within the room, attach the agent owner's profile to those timeline messages, and render a 16px owner badge between the agent name and timestamp without increasing row height. The owner popover label now reads Username's {agentname}., and avatar-less owners paint initials immediately instead of showing an empty fallback window.

File changes

desktop/playwright.config.ts
Adds the duplicate-agent avatar smoke spec to the smoke project so the user-facing timeline behavior runs in CI.

desktop/src/features/channels/ui/ChannelScreen.tsx
Fetches second-level agent owner profiles and merges them into the timeline profile lookup so owner badges have display names and avatars even when owners did not author messages in the room.

desktop/src/features/messages/lib/formatTimelineMessages.ts
Detects duplicate agent display names among room members and annotates only those agent messages with owner profile data for rendering.

desktop/src/features/messages/lib/formatTimelineMessages.test.mjs
Adds unit coverage for duplicate-name detection, unique-agent omission, human-author omission, missing owner handling, unknown owner fallback, and case-insensitive matching.

desktop/src/features/messages/types.ts
Adds agentOwner metadata to timeline messages for duplicate-agent disambiguation.

desktop/src/features/messages/ui/MessageRow.tsx
Renders the inline owner avatar between the agent name and timestamp, keeps it within the row line box, and passes the disambiguated popover label.

desktop/src/features/profile/hooks.ts
Adds a helper query for fetching profiles referenced by agent ownerPubkey fields.

desktop/src/features/profile/ui/UserProfilePopover.tsx
Allows the popover header display name to be overridden for the Username's {agentname}. label.

desktop/src/shared/ui/UserAvatar.tsx
Adds the 16px 2xs avatar size and renders initials immediately when there is no image source, avoiding an empty fallback window.

desktop/tests/e2e/duplicate-agent-avatars.spec.ts
Adds smoke coverage for two same-named agents and one unique control: loaded owner image, initials fallback, no badge for the unique agent, unchanged row height, and the requested popover copy.

Reproduction Steps

1. Open a room with two agents that share the same displayed name and a third uniquely named agent.
2. Confirm the duplicate-named agents show a small owner badge between the agent name and timestamp.
3. Confirm one owner badge can render an avatar image and another can render initials when no avatar URL exists.
4. Confirm the uniquely named agent has no inline owner badge.
5. Hover a duplicate-named agent and confirm the balloon reads Username's {agentname}..
6. Compare duplicate and unique rows and confirm the inline badge does not increase row height.

Screenshots/Demos

Timeline — Scout A shows alice's teal avatar image inline, Scout B shows bob's B initials, and Ranger shows no badge. Row heights match.

Balloon — duplicate-agent popover reads alice's Scout..

Validation

• pnpm --dir desktop check
• pnpm --dir desktop typecheck
• pnpm --dir desktop test
• pnpm --dir desktop build
• pnpm --dir desktop exec playwright test duplicate-agent-avatars --project=smoke
• Marge live-build gate on the feature branch before rebase: biome check, typecheck, 1481 unit tests, build, and duplicate-agent e2e cold 3/3 all green. I rebased onto latest origin/main before opening this draft PR and reran the focused validation above.