docs: fix DeepWiki badge

[imbajin]

Purpose of the PR

The Ask DeepWiki badge renders as a broken image when its origin returns an anti-bot challenge (HTTP 429; GitHub image proxy returns 502).

Main Changes

Use a static Shields badge while preserving the existing label and DeepWiki repository link.

Verifying these changes

• Trivial documentation-only change; git diff --check passes and the replacement returns a valid SVG.
• The DeepWiki destination still returns an anti-bot challenge during verification; the link is unchanged.

Does this PR potentially affect the following parts?

• Dependencies
• Modify configurations
• The public API
• Other affects
• Nope

Documentation Status

• Doc - TODO
• Doc - Done: README.md is updated in this PR.
• Doc - No Need

[imbajin]

Independent documentation cross-review of the current revision: 9/10; no blocking findings.

The complete diff changes only the README badge image source. The Markdown link structure, descriptive 'Ask DeepWiki' alternative text, and existing repository destination are preserved. This is a suitably small fix with no runtime or CI configuration changes.

Current workflow passed its license/policy job; build and cluster jobs were skipped. Independent HTTP/XML verification retrieved the replacement as HTTP 200 image/svg+xml with well-formed SVG and the expected accessible label. The unchanged destination returned cached HTML; fresh origin availability and GitHub image-proxy/browser rendering remain unverified.