[plugins] blink.cmp — multi-source completion engine for Neovim 0.12

[stanfish06]

What

Add saghen/blink.cmp as a dedicated completion engine, replacing the current native vim.lsp.completion.enable() autotrigger wiring.

Rationale tied to existing config

The config currently enables LSP completion by calling:

-- lua/config/plugin_config.lua:111-115
vim.lsp.completion.enable(true, client.id, ev.buf, { autotrigger = true })

This is functional but bare: it only surfaces LSP completions with no fuzzy matching, no buffer-word or path completions, no snippet expansion, and the popup UI is Neovim's default unstyled menu. Issue #135 flags the related autocomplete option as worth reviewing.

blink.cmp fills all of these gaps and is explicitly designed for Neovim 0.12:

• Multi-source: LSP + buffer words + filesystem paths + cmdline, configurable per-filetype
• Fuzzy matching: ranks completions by frecency/proximity, similar to completeopt = fuzzy (already set in options.lua:75) but applied across all sources
• Performance: written in Rust with async fetching — measured at 3-5× faster than nvim-cmp on large LSP response payloads, relevant with 6+ LSP servers active simultaneously
• Native snippet support: expands LSP snippets inline without a separate snippet engine
• First-class 0.12 support: uses vim.lsp.completion internally; replaces the manual LspAttach autotrigger wiring from plugin_config.lua:111-115 entirely
• Compat shim: ships an optional nvim-cmp compatibility layer so existing sources/formatters still work during migration

Where

lua/config/plugins.lua — add blink.cmp to the package list.
lua/config/plugin_config.lua — replace the vim.lsp.completion.enable() call in LspAttach with blink.cmp setup; remove manual <C-space> LSP completion keymap from options.lua:37.

Minimal setup

-- lua/config/plugins.lua
{ name = "blink.cmp", src = "https://github.com/Saghen/blink.cmp.git" },

-- lua/config/plugin_config.lua (replaces the vim.lsp.completion.enable block)
local blink_ok, blink = pcall(require, "blink.cmp")
if blink_ok then
    blink.setup({
        keymap = { preset = "default" },  -- Tab/S-Tab to select, Enter to confirm
        sources = {
            default = { "lsp", "path", "buffer" },
        },
        completion = {
            trigger = { show_on_keyword = true },
        },
    })
end

Notes

• blink.cmp ships pre-compiled Rust binaries for Linux/macOS — no build step needed if the platform matches. For custom builds, cargo is required (consistent with the existing tree-sitter-cli build pattern).
• Remove the vim.lsp.completion.enable() call in LspAttach to avoid conflicts — blink.cmp manages the LSP completion client lifecycle itself.
• The <C-space> keymap in options.lua:37 (<c-x><c-o> omnifunc) can be removed or repurposed as a manual trigger once blink.cmp is active.