fix(opencode): surface workflow descriptions to LLM via tool description

[mrsimpson]

Problem

OpenCode does not propagate Zod parameter .describe() text to the LLM. This meant the AI had no guidance on which workflow enum value to pick when calling start_development, leading to wrong workflow selection.

Root cause confirmed: Hardcoding a canary string via .describe() was completely invisible to the LLM — parameter descriptions are simply never surfaced by OpenCode, regardless of Zod version or registry.

Solution

Embed the workflow enum choices and their descriptions directly in the tool description string — the only channel confirmed to reach the LLM:

Start a development workflow.

workflow parameter — available values:
  - epcc: EPCC — <description>
  - bugfix: Bugfix — <description>
  - custom: Use a custom workflow name

Changes

• start-development.ts: Build tool description with inline workflow list; remove .describe() from workflow arg; remove unused generateWorkflowDescription import
• plugin.ts: Remove tool.definition hook (was attempting to bridge Zod registries — wrong approach)
• Development plan updated with full research trail of all 13 investigated approaches

Testing

All 286 tests pass. Verified the description is visible to the LLM after restart.