Deprecate asm.js builds and add inline WebAssembly variants

[lovasoa]

The asm.js builds are being deprecated as Emscripten prepares to remove wasm2js support. Applications that used them to avoid a separate Wasm asset can now import sql.js/dist/sql-wasm-inline.js and call initSqlJs() without locateFile configuration.

• Add optimized and debug inline WebAssembly builds, plus matching worker bundles, using SINGLE_FILE=1. Use base64 embedding so pages do not need to declare UTF-8 encoding.
• Keep the existing asm.js builds in npm and sqljs-all.zip during the grace period. Each warns once on initialization, links to Removing wasm2js (asm.js) support #635, suggests the inline variant, and invites users who cannot migrate to report their constraints.
• Replace standalone asm.js release downloads with the inline WebAssembly downloads. Update README, API documentation, RequireJS example, package metadata, and CI test scripts to feature WebAssembly builds. Automated tests cover only WebAssembly variants; deprecated builds were verified manually once.
• Add distribution checks for initialization with companion-asset loading disabled, isolated single-file Node.js use, and worker queries.

Validation: built all distributions with the pinned Emscripten 5.0.0; npm test passed (24 API checks on each of five Wasm variants plus distribution checks); one-time manual verification passed all three deprecated main-build API suites and checked once-only warnings on the five deprecated main/worker variants; npm run doc, npm pack --dry-run, and git diff --check passed. Additional Chromium checks exercised optimized/debug inline main and worker builds on a page without a charset declaration and confirmed zero .wasm requests. Distribution checks also passed with Node.js 24.

Refs #635 and #635 (comment).