[Docs] Add full deployment & initialization guide

[Jayrodri088]

Complexity / points: Medium (150 points) - maintainer label: points-150-medium

PR must include:

• Closes #20 in the PR description
• Tests added or updated where behavior changes
• Docs updated if public API, lifecycle, or deploy steps change
• No unwrap() in production Soroban contract paths (project convention)
• cargo test passes locally; match CI (cargo fmt, cargo clippy -D warnings) when touching Rust

Problem

Readme.md shows a deployment/invoke example, but it only demonstrates deploying invoice_escrow and calling initialize.

For real usage, contributors still need guidance for deploying and initializing:

• invoice-token (including how to set invoice_id and minter relationship)
• payment-distributor (once implemented)

This leads to confusion about the correct initialization order and what values need to be consistent across contracts.

Proposed change

Extend the repo documentation with a “Deployment & Initializationâ€^] section that covers the full sequence for all contracts in this repo.

Acceptance criteria

• README includes step-by-step deployment/invocation flows for:
  • invoice-token deployment + initialize
  • invoice-escrow deployment + initialize
  • (optionally) payment-distributor deployment once its API exists
• Clearly documents cross-contract wiring constraints, such as:
  • invoice-token.minters relationship (escrow contract address)
  • who is admin/platform recipient
  • fee bps value constraints
  • how invoice_id / Symbol should be chosen and used consistently
• Uses placeholders (no secrets) and aligns with .env.example
• Includes example Soroban CLI commands that match READMEΓò¼├┤Γö£ΓòóΓö¼├║╬ô├╢┬ú╬ô├╢├⌐╬ô├▓┬╝Γö£Γöñ╬ô├╢┬ú╬ô├«├ë╬ô├╢┬╝╬ô├▓┬Ñ╬ô├▓┬╝Γö£Γöñ╬ô├╢┬úΓö£ΓûÆ╬ô├╢┬ú╬ô├╢├⌐s soroban contract deploy usage

Dependencies

Recommended after [Docs] Add missing docs/API.md... so the deployment guide can link to authoritative function signatures.

[Jayrodri088]

Deferred (Wave 1 scope)
Maintainers are focusing this wave on implementation: escrow, invoice-token lifecycle, settlement/payment flows, payment-distributor, tests, and security bugs — aligned with decentralized invoice factoring on Stellar (liquidity for sellers, yield for investors, on-chain escrow/settlement).

Documentation issues will be reopened or recreated in a later wave. If you already started work, comment here and we can link a follow-up issue.