ci: add contract WASM size guard

[YfengJ]

Closes #748.

Summary:

• add a CI guard that checks the optimized token factory WASM size after the release build
• add a small Node script with a default 64 KiB Soroban limit and a workflow_dispatch override
• cover the size checker with node:test cases for default limits, invalid limits, pass, and fail paths

Validation:

• node --test scripts/check-wasm-size.test.mjs
• cargo build --target wasm32v1-none --release (from contracts/)
• node scripts/check-wasm-size.mjs --file contracts/target/wasm32v1-none/release/token_factory.wasm --max-bytes 65536
• cargo test (from contracts/token-factory/)
• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/ci.yml"); puts "workflow yaml parsed"'\n- npx --yes prettier@3.3.3 --check .github/workflows/ci.yml scripts/check-wasm-size.mjs scripts/check-wasm-size.test.mjs\n- git diff --check\n\nNote: the Rust commands still emit existing deprecation warnings, but tests/build pass and the optimized token_factory.wasm is currently 49,973 bytes under the 65,536 byte limit.

[YfengJ]

CI note for reviewers:

• The new contract WASM size guard is running in the Contract Build job, and that job passed. The contract test job also passed.
• The optimized token_factory.wasm is currently 49,973 bytes under the 65,536 byte limit.
• The red checks appear to be existing repo/workflow-level issues outside this diff:
  • Frontend fails on repo-wide Prettier warnings in 53 existing files.
  • Rust Formatting reports existing formatting diffs in contracts/token-factory/src/lib.rs and src/test.rs; this PR does not touch those files.
  • Storybook fails because esbuild cannot be resolved while evaluating .storybook/main.ts.
  • End-to-End Tests fail because docker-compose is not available on the runner.
  • npm audit reports existing dependency advisories.

No follow-up code change appears needed for the WASM size check unless you want this PR to also address one of those broader workflow issues.