Step 22a/23 (Phase 6): Release — Create version bump + release prep scripts

[Jordan231111]

Summary

Create automation scripts for version bumping, tagging, and pre-release verification.

Depends On: All features and tests complete
Parent Issue: #14 (Final Release Preparation)

Key Changes

1. Create `scripts/bump_version.sh`:
   • Accept bump type: major, minor, patch
   • Use `cargo set-version --bump ` (requires `cargo-edit`)
   • Commit the version change
   • Create a git tag (`v`)
   • Print instructions for pushing (don't auto-push)
2. Create `scripts/prepare_release.sh`:
   • Run full verification: `cargo fmt --all -- --check`
   • Run `cargo clippy --all-targets --all-features -- -D warnings`
   • Run `cargo test --all-targets --all-features`
   • Run `cargo test -- --ignored`
   • Run `cargo test --doc`
   • Run `cargo audit` (if installed)
   • Build release: `cargo build --release`
   • Print binary size and SHA-256 checksum
   • Exit non-zero if any step fails
3. Both scripts use `set -euo pipefail` and portable shebang

Acceptance Criteria

• `bump_version.sh` correctly bumps version in Cargo.toml
• `bump_version.sh` creates a commit and git tag
• `prepare_release.sh` runs all verification checks (fmt, clippy, test, audit)
• `prepare_release.sh` builds release binary and prints checksum
• Both scripts fail cleanly on errors
• Scripts are portable (bash, no platform-specific assumptions)