chore(examples): enforce repository hygiene standards across examples/

[salazarsebas]

Background

Previous hygiene work (#117) addressed build artifacts, but inconsistencies remain: incorrect description fields in Cargo.toml, missing .gitignore files, stale Cargo.lock entries, and README.md files containing hardcoded deployment identifiers or promotional formatting that obscures technical content.

Objective

Apply consistent repository hygiene standards across all examples without altering contract behavior.

In scope

1. Correct inaccurate description fields in Cargo.toml (e.g., trading_card_game currently references tower defense).
2. Audit and remove any committed target/ or .wasm artifacts.
3. Ensure each example directory includes a .gitignore excluding target/.
4. Remove hardcoded contract IDs and deployment results from README.md files.
5. Normalize README.md tone to technical documentation standards; relocate marketing-oriented content where it impedes clarity.

Out of scope

• Functional contract changes.
• CI workflow modifications.

Definition of done

• git ls-files 'examples/**/target/**' returns no results.
• No hardcoded deployment contract IDs appear in example README.md files.
• cargo metadata --no-deps succeeds for every example without metadata inconsistencies.

[Jo-anny]

@Jo-anny has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I would love to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Jo-anny to this issue.

[Peolite001]

@Peolite001 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

i would love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Peolite001 to this issue.

[drips-wave]

Congratulations, @Peolite001! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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