fix(gemini-cli): Surface specific missing companion error instead of generic unavailable status

[anthonyhaussman]

Summary

Fix an issue where a missing opencode-gemini-auth companion package resulted in a generic Gemini CLI: Unavailable (not detected) status message instead of the intended actionable error.

Details

Why:
In version 3.8.3, changes to how the companion package is resolved led to a regression in error reporting. The hasGeminiCliQuotaRuntimeAvailable() function was checking for both the presence of valid OAuth configuration and the companion package.
When the companion package was missing, it returned false, which caused the entire provider to be marked as unavailable.
This early exit bypassed the fetch phase (queryGeminiCliQuota()) where the specific and actionable error (Install opencode-gemini-auth separately to enable Gemini CLI quota) is actually generated and returned to the user.

How:

• Removed inspectGeminiCliCompanionPresence from hasGeminiCliQuotaRuntimeAvailable().
• The availability check now only verifies that Gemini CLI auth configuration is present.
• Companion validation is now correctly delegated to the fetch phase (queryGeminiCliQuota()), which properly captures the companion state and surfaces the appropriate error message to the user if it's missing or incompatible.

Linked Issue

Current version :

> node ./dist/bin/opencode-quota.js show

[Copilot] (personal)
Quota                                          16d
████████████████████░░░░░░░░░░░░░░░░░░░   52% left

Gemini CLI: Unavailable (not detected)

Fix version:

> node ./dist/bin/opencode-quota.js show        

[Copilot] (personal)
Quota                                          16d
████████████████████░░░░░░░░░░░░░░░░░░░   52% left

[Gemini CLI]
Gemini Pro                                     24h
███████████████████████░░░░░░░░░░░░░░░░   59% left
Gemini Flash                                 23.5h
███████████████████████████████████████   99% left
Gemini Flash Lite                                 
███████████████████████████████████████  100% left

OpenCode Validation

• Current production released OpenCode version tested: 1.15.0
• Why this version is relevant to the fix: -

Quality Checklist

• I ran npm run typecheck
• I ran npm test
• I ran npm run build
• This is the smallest safe root-cause fix (no unnecessary hook/output mutation logic)
• I preserved behavioral invariants and updated/added boundary tests as needed
• I updated docs for user-facing workflow/command/config changes (README.md and CONTRIBUTING.md when applicable)
• For new API-key/token providers, I started from contributing/provider-template/ or explained why the template does not apply
• For provider setup/auth wording changes, I checked the relevant dummy .ts template in contributing/provider-template/ and verified README.md against src/lib/provider-metadata.ts (authentication/authFallbacks) and provider auth resolver/diagnostics behavior

[slkiser]

@anthonyhaussman thanks!