feat: add Rust host runtime boundary

[replghost]

Summary

• adds a minimal truapi-server crate for host runtime mechanics: SCALE frame codec, dispatcher, transport trait, and subscription lifecycle
• extends truapi-codegen with --rust-output to generate the Rust dispatcher and wire table from the existing Rust trait surface
• wires scripts/codegen.sh to regenerate the checked-in Rust dispatcher alongside the existing TS generated outputs
• adds golden/idempotence tests, frame codec tests, subscription lifecycle tests, and Rust/TS wire-table parity coverage

Scope

This PR intentionally does not add host business logic. It does not include wallet, statement-store implementation, payment logic, smoldot provider, permissions policy, native/mobile bridges, or platform callbacks.

Verification

• cargo +nightly rustdoc -p truapi -- -Z unstable-options --output-format json
• cargo run -p truapi-codegen -- --input target/doc/truapi.json --output /private/tmp/truapi-generated-ts --rust-output rust/crates/truapi-server/src/generated --codec-version 1
• cargo +nightly fmt --check
• cargo test -p truapi-codegen -p truapi-server --all-features
• cargo test --workspace --all-features
• cargo clippy --workspace --all-targets --all-features -- -D warnings

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	cargo/​tempfile@​3.27.0

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[pgherveou]

that's probably a dup of #104 ?

[replghost]

Closing this as superseded by the active Rust-core stack in #104.

The closest overlap is #254 for Rust dispatcher / wire-table codegen; the subsequent stack PRs (#255 and later) carry the intended truapi-server, runtime, WASM, and dotli integration direction. The small CI-hardening suggestion from this branch has been left on #253: #253 (comment)