Split IndexedDB bootstrap below the MSVC literal limit

[wieslawsoltes]

Problem

The IndexedDB compatibility bootstrap is one 19,859-byte raw C++ literal. MSVC rejects individual string-literal tokens above its C2026 limit, which breaks the Windows native package before any IndexedDB tests can run.

Change

• split the bootstrap at an existing JavaScript boundary into 7,963-byte and 11,896-byte adjacent raw literal tokens
• retain the compiled std::string_view byte-for-byte
• extend the portable bootstrap regression to enforce the per-token limit and the complete-source SHA-256
• preserve the service-worker literal contract added by the preceding Stream and cache admitted Code OSS webview resources #266 stack

Validation

• Windows 11 ARM64 VM, Visual Studio 2026 Build Tools MSVC: /std:c++20 /W4 /WX header compile passed with the exact header blob in this rebased commit
• bootstrap literal contracts: 3/3 passed
• extracted IndexedDB JavaScript: Node syntax check passed
• AppleClang strict header compile and 19,859-byte static assertion passed
• exact full-source SHA-256 remains a3c907644e9b6c9d63eddfbd6a591802e99bbd3249a3b1437788ce4eb1c73b64
• git diff --check

This fixes the independent Windows C2026 package failure and does not change IndexedDB behavior.

Closes #301