Allow dev/gen-proto to supply a different proto path

[xmtp-coder-agent]

Resolves #73

Summary

• dev/gen-proto now accepts an optional positional argument for the proto path
• Falls back to the default buf.build/xmtp/proto when no argument is provided

Usage

# Default behavior (unchanged)
./dev/gen-proto

# Custom proto path
./dev/gen-proto buf.build/other/proto

Test plan

• Run ./dev/gen-proto with no arguments — should behave identically to before
• Run ./dev/gen-proto <custom-path> — should use the provided path instead

🤖 Generated with Claude Code

Note

Allow dev/gen-proto to accept a custom proto source path argument

Adds a PROTO_PATH variable to dev/gen-proto that reads the first positional argument, defaulting to buf.build/xmtp/proto. The buf generate call now uses this variable instead of the hardcoded path, so a different proto source can be passed at the command line without modifying the script.

^{Macroscope summarized 70a12fd.}

[xmtp-coder-agent]

The Buf CI failure is a pre-existing issue — the buf-push-action step requires a BUF_TOKEN secret which is not available on fork PRs. All recent PRs (#71, #69) show the same failure, while pushes to main succeed. This is unrelated to the change in this PR.