feat: replace npm live-server with pure-Lua HTTP server (#29)

## Problem

The plugin requires users to install Node.js and the `live-server` npm
package globally. This is a heavyweight external dependency for what
amounts to a simple local dev-server workflow, and it creates friction
for users who don't otherwise need Node.js.

## Solution

Replace the npm shell-out with a pure-Lua HTTP server built on `vim.uv`
(libuv bindings), eliminating all external dependencies. The new server
supports static file serving, SSE-based live reload, CSS hot-swap
without full page reload, directory listings, and recursive file
watching with configurable debounce.

Minimum Neovim version is bumped to 0.10 for `vim.uv` and `vim.ui.open`.
The old `args`-based config is automatically migrated with a deprecation
warning.

Closes #28.

doc/live-server.txt

@@ -7,13 +7,13 @@ Homepage: <https://github.com/barrettruth/live-server.nvim>
 INTRODUCTION                                                *live-server.nvim*
 
 live-server.nvim automatically reloads HTML, CSS, and JavaScript files in the
-browser via a local development server.
+browser via a local development server. No external dependencies required —
+the server runs entirely in Lua using Neovim's built-in libuv bindings.
 
 ===============================================================================
 REQUIREMENTS                                        *live-server-requirements*
 
-- Neovim >= 0.9.0
-- live-server npm package (`npm install -g live-server`)
+- Neovim >= 0.10
 
 ===============================================================================
 CONFIGURATION                                            *live-server-config*
@@ -22,15 +22,23 @@ CONFIGURATION                                            *live-server-config*
 Configure via `vim.g.live_server` before the plugin loads: >lua
 
     vim.g.live_server = {
-        args = { '--port=8080', '--no-browser' },
+        port = 8080,
+        browser = false,
     }
 <
                                                          *live_server.Config*
 Fields: ~
 
-    {args}  (`string[]`) Arguments passed to live-server via |vim.fn.jobstart()|.
-            Run `live-server --help` to see available options.
-            Default: `{ '--port=5555' }`
+    {port}      (`integer?`) Port for the HTTP server. Default: `5500`
+    {browser}   (`boolean?`) Auto-open browser on start. Default: `true`
+    {debounce}  (`integer?`) Debounce interval in ms for file changes.
+                Default: `120`
+    {ignore}    (`string[]?`) Lua patterns for file paths to ignore when
+                watching for changes. Default: `{}`
+    {css_inject} (`boolean?`) Hot-swap CSS without full page reload.
+                Default: `true`
+    {debug}     (`boolean?`) Log each step of the hot-reload chain via
+                |vim.notify()| at DEBUG level. Default: `false`
 
 ===============================================================================
 COMMANDS                                               *live-server-commands*
@@ -113,8 +121,32 @@ Lua keybinding to toggle server: >lua
 Configuration with custom port and no auto-open: >lua
 
     vim.g.live_server = {
-        args = { '--port=3000', '--no-browser' },
+        port = 3000,
+        browser = false,
     }
 <
+Ignore node_modules and dotfiles: >lua
+
+    vim.g.live_server = {
+        ignore = { 'node_modules', '^%.' },
+    }
+<
+===============================================================================
+KNOWN LIMITATIONS                                  *live-server-limitations*
+
+No Recursive File Watching on Linux ~
+                                              *live-server-linux-recursive*
+libuv's `uv_fs_event` only supports recursive directory watching on macOS
+(FSEvents) and Windows (ReadDirectoryChangesW). On Linux, the `recursive`
+flag is silently accepted but ignored because inotify does not support it
+natively. Only files directly in the served root directory trigger
+hot-reload; files in subdirectories (e.g. `css/style.css`) will not be
+detected.
+
+See https://github.com/libuv/libuv/issues/1778
+
+Enable `debug` in |live-server-config| to verify whether `fs_event`
+callbacks fire for a given file change.
+
 -------------------------------------------------------------------------------
 vim:tw=78:ft=help:norl: