fix(runtime): recover hydrated image context overflow

[Sun-GLiang]

Summary

• omit hydrated historical image tool results only after a provider context overflow, then preserve the exact omission across later requests
• keep the recovery to one shared retry and prevent the generic retry path from looping context overflow
• show dedicated Desktop guidance when the shortened request still exceeds the context window

Fixes #3372

Verification

• npm test
• npm run lint
• npm run format:check
• npm run build
• npm run typecheck
• npx knip --workspace apps/desktop
• npx knip --workspace packages/ui
• git diff --check

Visual evidence

Before — generic direct-retry guidance:

After — dedicated context-overflow guidance:

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the Runtime recovery, Desktop presentation, tests, documentation, and review fixes.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No