#255 refactor: move update_readme tool out of the library crate

[RAprogramm]

Closes #255

reqwest (a native blocking HTTP client, pulling hyper/tokio/etc.) and regex were declared as hard [dependencies] of the published crate but used only by the update_readme dev binary — so every downstream user of this WASM SDK compiled them for nothing.

Changes

• Moved src/bin/update_readme/ into a new non-published workspace member tools/update-readme with its own dependencies.
• Removed regex and reqwest from the library crate's [dependencies] (both unused by the library; percent-encoding and toml stay — used by core::context and the mock feature).
• The tool now resolves the repository root by walking up to the [workspace] Cargo.toml instead of CARGO_MANIFEST_DIR.
• CI refresh step runs cargo run -p update-readme; codecov ignores tools/**.

Result

cargo tree -p telegram-webapp-sdk (default features) now pulls no reqwest / regex / hyper / tokio. Verified: tool + lib tests green (23 + 182), cargo deny ok, clippy/fmt clean, README stays in sync (workspace-root resolution works), reuse lint passes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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