[PR #1] .gitignore missing Foundry artifacts: out/, cache/, broadcast/

[obchain]

PR: #1 (chore/bootstrap)
Commit: c104b60
File: .gitignore

Problem: .gitignore covers Rust artifacts (/target/, *.rs.bk) but omits standard Foundry output directories:

• out/ — compiled contract artifacts (ABI + bytecode JSON)
• cache/ — Foundry compilation cache
• broadcast/ — forge script output containing signed tx JSON (sender, gas params, raw tx hex)

README already references contracts/ with a Foundry suite (forge build && forge test). Without these entries, first forge build / forge script run produces untracked files that a careless git add . will commit.

Impact: broadcast/ leak has operational security implications — records deployment transactions and can aid reconstruction of key usage patterns. out/ and cache/ are bloat/noise.

Fix: Add to .gitignore:

# Foundry
out/
cache/
broadcast/

Or namespaced under contracts/ once the Foundry workspace lands (PR #11 / #36):

contracts/out/
contracts/cache/
contracts/broadcast/

Severity: High — broadcast/ leakage is a security concern.

[obchain]

Fixed on chore/bootstrap in 38e7eac.