Report contract wasm size on every CI run

[Olamidepy]

Wasm size directly impacts contract deployment costs, but was not previously tracked in CI. This change adds automatic measurement and reporting of the built contract Wasm size (tributary_splitter.wasm) during every CI run.

Changes Made
CI Workflow Update (

ci.yml
):
Scoped the contract job with pull-requests: write and contents: read permissions.
Added a step to measure the built Wasm binary size in both raw bytes and decimal KiB.
Added the formatted size breakdown to the Action run summary ($GITHUB_STEP_SUMMARY).
Added sticky PR commenting (via marocchino/sticky-pull-request-comment@v2) to post and update the size table directly on pull requests.

#91 resolved

[Olamidepy]

@Spagero763 kindly merge

[Spagero763]

contract fails with Configuration Error: Failed to read config file: ".cspellrc.json" (not an unknown-word failure — the spellcheck step can't find the config at all), and web is failing too. Worth checking whether this PR's CI changes touch the working directory the spellcheck step runs from, or whether updating your branch to current main resolves it.