[UI/UX] Implement search bar

[RalXYZ]

In #29 (comment), @lynzrand mentioned that he had proposed a search box design. We now want to implement this solution.

We expect the search box to exhibit the following behaviours:

• If the search box is empty, the current layout remains unchanged.
• If the search box contains any characters, the following actions occur:
  • Support fuzzy search.
  • Hide the "Popular Mirrors" and "Latest Update" components, and only display the cards within the "All Mirrors" section that match the search.
  • The matched characters in the mirror cards should be highlighted. In light theme, the highlight colour should be "创新红" #B01F24, one of the school colours of Zhejiang University.
• On the right side of the search box, there should be a CTRL K symbol to indicate to users that they can use this shortcut to enter content within the search box. Refer to the implementation on the CERNET mirror site.

[determ1ne]

A basic search bar with fuzzy search has been implemented in ce0c8ea. Further style tweaks are still needed.