feat: initial blink-cmp-ssh implementation

Problem: the existing blink-cmp-sshconfig plugin uses a synchronous,
build-time Python scraping approach that requires uv and make to
generate a static Lua file.

Solution: implement a runtime, async blink.cmp source that parses
ssh_config keywords from man ssh_config and enum values from ssh -Q
queries, matching the architecture of blink-cmp-tmux and
blink-cmp-ghostty.

stylua.toml

@@ -0,0 +1,8 @@
+column_width = 100
+line_endings = "Unix"
+indent_type = "Spaces"
+indent_width = 2
+quote_style = "AutoPreferSingle"
+call_parentheses = "Always"
+[sort_requires]
+enabled = true