[Feat] genearted code based on description inside a sub window buffer

[PyDevC]

Feature Introduction: When the cursor line is a comment (detected via Treesitter or synID), use a different prompt template that instructs the model to generate the code described by the comment when a special request of auto-complete the function is called.

Feature Description:

-- User writes:
-- parse CSV file and return rows as objects
local function parse_csv(filepath)
end

-- user selects whole block of code

-- Model generates:
local function parse_csv(filepath)
    local rows = {}
    for line in io.lines(filepath) do
        table.insert(rows, vim.split(line, ","))
    end
    return rows
end

1. Detect comment lines via vim.fn.synID or Treesitter comment nodes
2. Use a different system prompt for comment-to-code mode
3. Return multi-line blocks with proper indentation
4. Fall back to normal completion if cursor is on code

Is your feature possible with the current status of repo? Yes. Requires a new prompt template and comment detection logic. Already have language detection via Treesitter.