docs: improve documentation for deployed programs

[airope]

Summary

Closes #3800

Improves the deployment documentation for contracts, predicates, and scripts with the following enhancements:

• Added Sway source examples to each deployment guide so users can see the program being deployed
• Documented both deployment mechanisms (CLI via fuels deploy and dynamic/programmatic deployment) across all three program types
• Restructured deploying-contracts.md to clearly separate CLI vs dynamic deployment paths
• Improved managing-deployed-contracts.md to lead with the most common use case (connecting to an already-deployed contract)
• Added cross-references between deployment and managing docs for better discoverability

Checklist

• Documentation changes only
• Addresses all enhancement suggestions in Improve documentation for deployed programs #3800

[cursor]

PR Summary

Low Risk
Documentation-only updates; primary risk is minor user confusion if CLI/programmatic steps or code snippet anchors are incorrect.

Overview
Clarifies program deployment docs by explicitly separating CLI (fuels deploy) vs dynamic/programmatic deployment flows for contracts, predicates, and scripts, and adds embedded Sway source examples to each guide.

Reworks managing-deployed-contracts.md to lead with connecting to an existing contract (contract ID + ABI), adds guidance for B256 contract IDs, and adds a Next steps cross-link from contract deployment to contract management.

Also updates .gitignore to ignore .claude/ and adds region markers to the example Sway contract used in docs.

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