feat(miniapp): integrate PPT Live with the shared agentic bubble

[bobleer]

Summary

• move PPT Live launcher guidance to the bottom-right safe area and refine the in-app Agentic entry CTA
• create a dedicated hidden Agent session for every new deck topic, restore the persisted session and history for existing topics, and restore the prior normal chat when the bubble closes
• keep FloatingMiniChat as the single standard chat window: it always renders the shared ChatPane and full ChatInput
• add a generic ChatInputRegistration extension contract for bounded placeholder/workspace/draft content and submission routing; MiniApps cannot replace or resize the composer
• forward normalized shared-composer submissions (text, display text, contexts, composer presentation, session and workspace) to the token-scoped MiniApp runner
• let Agentic MiniApps register host-rendered title/welcome/suggestions and use their manifest icon for the launcher while all markup, theme, attachments, model, voice, permission, stop and input state stay host-owned
• isolate the registered input and workspace strip to the active MiniApp topic workspace so the normal project never leaks into PPT Live
• track a MiniApp-owned hidden session independently of the globally active chat, and show a neutral rotating ring plus glow around its launcher for the full non-terminal turn lifecycle; provide a static reduced-motion fallback
• migrate PPT Live off the removed private textarea/panel-size path and bump the built-in bundle to version 257
• raise the shared body-portaled model selector to the semantic popover layer so it remains visible and interactive inside overlay-hosted surfaces such as FloatingMiniChat
• document the shared-component extension boundary and add regression tests that reject any MiniApp-specific composer or panel shell

Verification

• pnpm run type-check:web
• focused Vitest: chatInputRegistration.test.ts, miniAppStore.test.ts, toolbarModeSessionSurface.test.ts (25 tests)
• focused Vitest: ModelSelectorPortalLayer.test.ts, modelSelectorDropdownPosition.test.ts (4 tests)
• focused Vitest: floatingMiniChatActivity.test.ts (10 tests)
• node src/crates/contracts/product-domains/src/miniapp/builtin/assets/ppt-live/test/generated-file-protocol.test.mjs (50 tests)
• cargo test -p bitfun-product-domains --features product-full ppt_live_bundle_uses_bitfun_host_capabilities
• pnpm run theme:color-audit:all
• targeted ESLint for the changed Web UI TypeScript/TSX files
• git diff --check
• browser visual QA at 1280×720 with the real FloatingMiniChat: standard panel dimensions and full shared composer rendered; the PPT example populated chat-input-textarea; MiniApp workspace strip showed ppt-live-deck; no private textarea or layout overlap
• browser interaction QA with the real shared ModelSelector: reproduced the open menu at z-index 60 underneath the floating surface at 101; verified the fix renders it at the popover layer (360), then selecting qa-fast closes the menu and updates the trigger
• browser activity QA with a normal chat kept globally active and a separate bound MiniApp session processing: the launcher exposed aria-busy=true, the ring transform and glow changed over time, the decoration kept pointer-events:none, clicking still opened the shared panel, and completing the turn removed the indicator, processing class, and busy state
• earlier commits in this PR also passed Web lint, MiniApp/session Rust checks, desktop check, i18n audit, repo hygiene, and all upstream CI jobs

AI-assisted; locally verified at the levels listed above.