docs(openrouter-images): sync with openrouter-web changes

[devin-ai-integration]

Summary

Syncs the images skill with capability-aware routing shipped in OpenRouterTeam/openrouter-web#27653:

• Sending a parameter supported by only some of a model's endpoints no longer risks a 400 — routing drops incapable endpoints and reroutes to a sibling that advertises the value.
• A parameter no endpoint supports now returns a field-scoped 400 naming the field and value (e.g. resolution "4K") with each provider's rejection reason.
• A tier-shaped size (e.g. "4K") is folded into resolution for the capability check.

Updated the "Discover Capabilities First" and "Options" sections in SKILL.md accordingly.

Link to Devin session: https://openrouter.devinenterprise.com/sessions/673fa7d886684d739ea453d424a941c7

[devin-ai-integration]

Original prompt from Automation

You are the public skills sync pipeline. Your job is to scan PRs merged to main on OpenRouterTeam/openrouter-web in the last 24 hours, determine if any changes warrant updating the public agent skills in OpenRouterTeam/skills, and open PRs to the skills repo when updates are needed.

#``# Step 1: Identify relevant merged PRs

Clone both repos:

cd /home/ubuntu/repos/openrouter-web
git fetch origin main
git log --since='24 hours ago' --merges --first-parent origin/main --pretty=format:'%H|%s' --name-only

For each merged PR, collect the list of changed files. Only PRs that touch the paths in the mapping below are relevant. Skip bot commits (devin-ai-integration[bot], Devin AI, GitHub Actions Bot, openrouter[bot], opencode-agent[bot], OpenRouter SDK Bot, Claude, detail-app[bot], forge-the-devex-intern[bot], dependabot[bot]).

If no relevant PRs were merged, post a short message to the #devrel Slack channel (C08LQFVSC7Q) saying no skill-relevant changes were detected today, and exit.

#``# Step 2: Map changed files to affected skills

Use this mapping to determine which public skills are potentially affected:

openrouter-web paths	Affected skill(s) in OpenRouterTeam/skills
sdks/typescript/, packages/llm-interfaces/	openrouter-typescript-sdk, openrouter-agent-migration
services/cfw-*/src/routes/*analytics*, analytics query/response schemas	openrouter-analytics, openrouter-analytics-query, openrouter-analytics-schema
Generation routes, /api/v1/generation	openrouter-generations
Image generation adapters, packages/image-generation/	openrouter-images
supabase/seeds/, model schemas, /api/v1/models route	openrouter-models
OAuth/auth routes, PKCE flow code	openrouter-oauth
STT adapters, services/cfw-stt-api/, /api/v1/audio/transcriptions	openrouter-stt
TTS routes, /api/v1/audio/speech	openrouter-tts
Video adapters, /api/v1/videos	openrouter-video
``@`openr... (3383 chars truncated...)

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR that start with 'DevinAI' or '@devin'.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring