feat(opencode-plugin): instruct model to create branch with conventional prefix

[mrsimpson]

Summary

• When no workflow is active, the opencode plugin now instructs the model to first create a branch with a meaningful name using conventional commit prefixes (e.g., feat/add-new-feature, fix/bug-description, refactor/improve-logic) before calling start_development
• Modified both "no active workflow" message locations in plugin.ts (lines 381 and 400) to include branch creation guidance

Motivation

Previously, the plugin would instruct the model to call start_development without first creating a properly named branch. This change ensures that development sessions start with good git hygiene by following conventional commit naming conventions for branches.

Changes

• packages/opencode-plugin/src/plugin.ts: Updated the "No Active Workflow Detected" message text in both injection points (handler failure path and CONVERSATION_NOT_FOUND error path) to include branch creation instructions with conventional commit prefix examples

Testing

• Verified the changes via git diff to ensure both message locations were updated correctly
• No tests were modified (change is a simple string literal update)
• Code cleanup completed: no debug output, TODO/FIXME, or debugging code blocks found

Related

Implements feature request to improve workflow initialization experience by ensuring proper branch naming from the start.