[Web/PWA] Run end-to-end desktop and Android PWA acceptance pass

[AlphaMao1]

Parent

#11

What to build

Run the final acceptance pass that proves the Web/PWA rebuild is not a static shell. This issue should exercise the full path on desktop and Android Chrome/PWA with real Supabase behavior and at least one live provider smoke test.

Acceptance criteria

• A clean desktop browser session can sign in, upload an EPUB, index it, read, highlight, ask AI, save a memory, export Markdown, and delete the book.
• A second browser profile or device can restore the same EPUB, progress, annotations, default conversation, and memories.
• A real Android Chrome/PWA run verifies the narrow-screen reader, selection menu, and bottom-sheet chat.
• Offline reading is tested by disabling network after cache, updating progress/highlight locally, restoring network, and confirming sync.
• Supabase RLS and private Storage are smoke-tested against cross-user access.
• Inspection confirms provider API keys are not written to Supabase.
• At least one live embedding provider call and one live chat provider call are verified, with rate-limit/error behavior documented.
• No acceptance step relies on a hardcoded demo book, fake indexing progress, mock-only sync, skipped deletion, or desktop-only APIs.

Blocked by

• [Web/PWA] Add Markdown export and deletion semantics #20
• [Web/PWA] Run original release parity and visual QA pass #30