feat: add shared cross-contract view helpers

[Silver36-ship-it]

Closes #865

Summary

Describe what changed and why.

Linked Issue

Closes #

Type of Change

• feat
• fix
• docs
• refactor
• test
• chore

Validation

• Lint passed for affected area(s)
• Tests passed for affected area(s)
• Manual verification completed (if applicable)

Documentation

• Documentation updated (or N/A with explanation)
• Screenshots/videos attached for UI changes

Checklist

• Branch name uses feat/, fix/, or docs/
• Commit messages follow Conventional Commits
• PR scope matches linked issue acceptance criteria

PR Summary

This PR introduces a shared helper library for safe, reusable cross-contract reads in the Soroban on-chain workspace.

What changed

• Added a new shared helper crate for cross-contract view calls
• Implemented reusable helpers for:
  • generic view invocation
  • boolean view reads
  • unsigned integer view reads
• Updated the project registry contract to use the shared helper for reputation and registration lookups
• Updated the community curation contract to use the shared helper for reputation and total-reputation reads
• Standardized error handling by mapping shared view failures into each contract’s own error enum
• Added documentation describing intended usage and error handling patterns

Why

This removes duplicated cross-contract read logic across modules and provides a consistent approach for safe read-only contract interactions.

Benefits

• Reduces duplicate code
• Improves consistency across contracts
• Standardizes failure handling for cross-contract reads
• Makes future contract integrations easier to implement safely

Validation

• Reviewed the updated contract files and helper crate
• Confirmed the new helper is used by multiple contracts
• Verified the implementation is scoped to the relevant on-chain contract packages and docs

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[Cedarich]

Kindly fix failing CI

[Cedarich]

@Silver36-ship-it

[Cedarich]

@Silver36-ship-it

[Cedarich]

@Silver36-ship-it