docs: refresh bilingual READMEs and product showcase assets

[GCWing]

Summary

The READMEs told different product stories and used outdated branding and evaluation images. Rewrite the Chinese edition around the product's capabilities, then rebuild the English edition with matching content and natural English copy.

• Present the four modes, device continuity, Mini Apps, specialist agents, customization, and the DeepSWE v1.1 results.
• Add the shared wordmark and showcase images, and remove five superseded README assets.
• Keep connection, deployment, and installation instructions in collapsible sections.

Type and Areas

Type: Documentation.

Areas: English and Chinese READMEs and their images.

Motivation / Impact

Give readers a consistent introduction in both languages, with clearer use cases and visual examples. Preserve access to setup instructions and contribution guidance.

Verification

• node scripts/check-repo-hygiene.mjs — passed during preparation.
• node scripts/product-identity-audit.mjs — passed during preparation.
• node scripts/check-git-object-sizes.mjs --base origin/main --head HEAD — all 8 introduced blobs are within the 5 MiB limit.
• git diff --check origin/main...HEAD — passed.
• Checked local README links, matching image order across locales, original image hashes, and removal of obsolete image references from both READMEs.
• Verified the final 13-file diff contains only README.md, README.zh-CN.md, and their assets under png/.

Reviewer Notes

AI-assisted; lightly tested. Uses the supplied showcase artwork and the existing official desktop screenshot. This is a documentation-only PR with no application or test-source changes. Browser rendering, E2E, and remote-device behavior were not exercised.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.