feat(search): add fuzzy subsequence matching

[guolingGithub]

Summary

• Implement ROADMAP feat(core,react,vue,search,slash,toolbar): editor API, search, slash commands and toolbar enhancements #17 fuzzy search as an opt-in mode for in-document find/replace.
• Add fzf-style ordered subsequence matcher (tbe → table), Fuzzy toggles in plugin-search panel + electron-demo search bar, and table-highlight/navigation/replace support.
• Keep default literal search unchanged; Fuzzy and Regexp are mutually exclusive.

Test plan

• pnpm vitest run packages/plugin-search/test/plugin-search.test.ts passes
• Demo: open search (Cmd/Ctrl+F), check Fuzzy, search tbe against text containing table and confirm a hit
• Uncheck Fuzzy and confirm tbe returns 0 results
• Fuzzy replace / replace-all works without overlapping corruption
• Regexp checkbox disables when Fuzzy is enabled (and vice versa)

Notes

• Branch: feat/fuzzy-search (personal fork). Do not merge unless maintainers approve.
• AI assistance used for implementation scaffolding; design/tests reviewed for subsequence matching + non-overlapping replace semantics.

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