chore: add copyright headers to web lib core helpers

[karagozemin]

Add a per-file copyright header so ownership is visible at the file level (consistent with the root LICENSE).

Mechanical change — prepend this exact line as the first line of each file, nothing else:

// Copyright (c) 2026 Sub Rosa contributors

Add it to the following files:

• apps/web/src/lib/chain.ts
• apps/web/src/lib/config.ts
• apps/web/src/lib/demoActions.ts
• apps/web/src/lib/demoTypes.ts

[bobo-24]

Hi! I came across this issue and would love to work on it. I have experience with similar tasks and I'm confident I can investigate, implement a clean solution, and thoroughly test it before submitting a PR. If the issue is still open, I would appreciate it if you could assign it to me. I’ll prioritize this immediately and ensure a reliable solution is delivered as soon as possible. Thank you!

[skull-X]

Hi 👋
I’m a blockchain developer with strong expertise in Stellar, Rust,TS and Stellar SDK integrations. I’ve worked on multiple Stellar-based smart contract and backend systems.

ETA: 34 hours

[Olasunkanmi975]

I have a solid understanding of the underlying architecture required for this task and am ready to start testing a solution immediately.

[s6pa1rta3n-lab]

/try

I am working on adding the copyright headers to the web lib core helpers as specified in the issue description.