docs: add tutorial for reporting typosquats and claiming bounties (closes #158)

[dezzy-music]

Description

Adds docs/tutorial.md providing an end-to-end guided walkthrough from initial detection to receiving on-chain payment:

1. Scanning candidate package names using cargo run --bin scan (demonstrating edit distance, homoglyph impersonation, and clean baseline results).
2. Verifying package metadata and filing upstream disclosures to package registries.
3. Querying on-chain bounties on Stellar testnet.
4. Submitting claims with proof writeup references.
5. Review, junk-claim rejection, and admin payout release with live transaction links.
6. Monitoring the findings on the web dashboard.

Closes #158

---

Tasks Completed

• Written docs/tutorial.md with real commands, outputs, and contract data.
• Linked the tutorial under ## Documentation in README.md.
• Verified all commands (scan, client) and explorer links against testnet data.
• Added progress entry in PROGRESS.md.

---

Acceptance Criteria

• Every command in the tutorial was run while writing it
• All commands and links in the new docs have been verified
• PROGRESS.md entry added, and the PR description includes Closes #158

---

Stellar Address (Stellar Wave Program)

GDLCJGQLXZGDAAT5QGRF6FM2MBEER3FPYGCSVPXYL47G2ABIOX2M2S6K