feat: add opt-in Godot run console capture

[Mathijs-Bakker]

Implemented opt-in live Godot run output capture.

The new console module is in lua/godotdev/run_console.lua:1. When run.console.enabled = true, the :GodotRun* commands route through it from lua/godotdev/run.lua:163 instead of the old detached launch path. It supports a split buffer or float, reuses the console buffer, exposes :GodotShowConsole, and captures one active Godot run at a time.

The new config is wired into lua/godotdev/setup.lua:21, and the usage/docs were added in README.md:173 and README.md:377. Tests were added in tests/spec_run_console.lua:1, and the full suite passes with nvim --headless -u NONE -i NONE -c "lua dofile('tests/run.lua')" -c qa.

To enable it:

  require("godotdev").setup({
    run = {
      console = {
        enabled = true,
        renderer = "buffer", -- or "float"
      },
    },
  })

One behavior change is intentional: with console capture enabled, those Godot runs are no longer detached from Neovim.