feat(web-ui): add desktop pet bubble composer

[bobleer]

Summary

• add an inline composer to Agent companion task bubbles with send, cancel, Enter, and Escape interactions
• make the composer affordance appear reliably before the transparent pet window is focused by extending the existing cursor-position hover polling to bubbles
• add pet and bubble context-menu actions, task dismissal handling, and a main-window command bridge
• widen bubbles to 180px, align composer controls with bubble copy, and add localized labels for supported locales
• add focused component and command-handler coverage

Fixes #987

Type and Areas

Type:

Feature / bug fix / UI/UX / test

Areas:

Web UI, desktop Agent companion window, flow-chat activity, i18n

Motivation / Impact

Users can reply directly from a desktop pet task bubble without opening the main BitFun window. The hover affordance now works while the transparent pet window is inactive, disappears reliably when the pointer leaves, and the inline composer provides explicit send and cancel controls. Context menus also allow closing the pet or dismissing individual task bubbles.

Verification

• pnpm --dir src/web-ui run test:run src/app/components/AgentCompanionDesktopPet/AgentCompanionDesktopPet.test.tsx src/app/services/agentCompanionPetCommands.test.ts src/flow_chat/services/AgentCompanionActivityBridge.test.ts src/infrastructure/mouse-glow/core/MouseGlowService.test.ts — 4 files, 31 tests passed
• pnpm run type-check:web — passed
• pnpm run i18n:audit — passed with 0 warnings
• pnpm --dir src/web-ui exec sass src/app/components/AgentCompanionDesktopPet/AgentCompanionDesktopPet.scss /tmp/bitfun-agent-pet-cancel.css — passed
• git diff --check — passed

Reviewer Notes

• macOS/Linux use cursor-position polling for hover because an inactive transparent pet window does not reliably receive native hover events; Windows retains native hover behavior.
• Direct replies are limited to normal sessions; child/review contexts continue to open in the main window.
• AI-assisted implementation; fully locally verified with the commands above.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.