fix: add missing imageRequestPricing method to ZenAdapter

[superzzm2026]

Problem

When using the opencode2dsh plugin with DSH Desktop, running /compact throws:

TypeError: this.adapters.get(...)?.adapter.imageRequestPricing is not a function

Root Cause

The ZenAdapter class (structural LlmAdapter implementation) does not implement the imageRequestPricing method. The LlmAdapter base class in @deepseek-ai/dsh-llm defines imageRequestPricing(_provider, _model) {} as a default no-op. Since ZenAdapter uses structural implementation, it must explicitly implement this method.

Fix

/** No image pricing for the free Zen lane. */
imageRequestPricing(_provider: string, _model: string): undefined {
  return undefined
}

Impact

• Severity: Medium — affects any user running /compact or image-related requests
• Scope: Single method addition, no behavioral change
• Risk: Zero — returns undefined (same as base class default)

Reproduction

1. Install @opencode2dsh/dsh-plugin (v0.3.1 ~ v0.3.3 all affected)
2. Run /compact in DSH Desktop
3. Observe: this.adapters.get(...)?.adapter.imageRequestPricing is not a function

[superzzm2026]

⚠️ Severity Update: High — Automatic Context Compression Broken

I want to highlight that this bug has a more critical impact than initially described:

This bug silently breaks DSH's automatic context compression (/compact).

When a conversation grows long, DSH automatically triggers /compact to compress the context and stay within token limits. Because imageRequestPricing is missing from ZenAdapter, this auto-compression crashes every time with:

TypeError: this.adapters.get(...)?.adapter.imageRequestPricing is not a function

Consequences:

• Long conversations cannot be automatically compressed, leading to context overflow
• Users may experience silent context loss, degraded model responses, or session errors
• Manual /compact also fails with the same error
• This affects every user of the opencode2dsh plugin (v0.3.1, v0.3.2, v0.3.3)

The fix is a single method addition that returns undefined (matching the base class default), with zero risk of behavioral change.