[FEATURE]: Abbreviation-based model selector search (e.g. deepff → Deepseek V4 Flash Free)

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Describe the enhancement you want to request

The model selector's search currently supports exact substring matching (e.g. typing "deepseek" matches "Deepseek V4 Flash Free") and compact matching (e.g. "deepseekv4" matches "Deepseek V4 Flash Free").

However, there is no abbreviation-based matching. When there are multiple similar models like:

• Deepseek V4 Flash Free
• Deepseek V4 Flash
• Deepseek V4 Pro

Users cannot type shorthand like deepff to narrow down to "Deepseek V4 Flash Free" or deepp to find "Deepseek V4 Pro". They must type the full model name or enough unique characters to disambiguate.

Proposed behavior:

Add a word-initial abbreviation matching mode. When a query contains characters that match the first letters of normalized words in a model name, treat it as a potential abbreviation match. For example:

• deepff → matches "Deepseek V4 Flash Free" (deep + f + f)
• deepp → matches "Deepseek V4 Pro" (deep + p)
• dvff → matches "Deepseek V4 Flash Free" (d + v + f + f)
• gp5 → matches "GPT 5.5" (g + p + 5)

This allows power users to quickly narrow down model lists without typing full names.