Improve dev host handling and clarify backend port configuration (#532)

* fix: remove --host from npm run server command

Running `vite --host` exposes the dev server on all interfaces. However,
we should expose it on all interfaces only when `HOST` is set to `0.0.0.0`.
Otherwise, we should assume the user wants to bind to a host of their choice
and not expose the server on the network.

* fix: use src hostname for redirecting to Vite in development

Previously, the server redirected to Vite using `localhost` as the hostname.
Even if the user was using HOST="0.0.0.0", if they connected to server from
another device on the same network using `http://<host_ip>:3001`, the
server would redirect them to `http://localhost:5173`, which would not
work since `localhost` would resolve to the client's machine instead of the server.

* fix: use shared network hosts configuration for better proxy setup

- Normalize all localhost variants to 'localhost' for consistent proxy
configuration in Vite and server setup.
- use one source of truth for network hosts functions by moving them to
a shared
- log production and development urls

* refactor: rename PORT to SERVER_PORT for clarity

* chore: add comments explaining host normalization

* fix: add legacy PORT env fallback for server port configuration

* fix: add fallback for SERVER_PORT using PORT environment variable

---------

Co-authored-by: Haileyesus <something@gmail.com>
Co-authored-by: Simos Mikelatos <simosmik@gmail.com>

server/routes/taskmaster.js

@@ -529,7 +529,7 @@ router.get('/next/:projectName', async (req, res) => {
             
             // Fallback to loading tasks and finding next one locally
             // Use localhost to bypass proxy for internal server-to-server calls
-            const tasksResponse = await fetch(`http://localhost:${process.env.PORT || 3001}/api/taskmaster/tasks/${encodeURIComponent(projectName)}`, {
+            const tasksResponse = await fetch(`http://localhost:${process.env.SERVER_PORT || process.env.PORT || '3001'}/api/taskmaster/tasks/${encodeURIComponent(projectName)}`, {
                 headers: {
                     'Authorization': req.headers.authorization
                 }
@@ -1960,4 +1960,4 @@ Brief description of what this web application will do and why it's needed.
     ];
 }
 
-export default router;
+export default router;