fix: smooth GUI during pipeline downloads and harden wizard connection test

GUI log batching (_poll_log now drains queue into a single CTkTextbox.insert
call per 80 ms tick instead of N calls, each with see("end") scroll).

_QueueWriter strips ANSI/CSI escape codes and bare \r before enqueuing so
tqdm progress output is legible in the log textbox. OSC sequences terminated
by both BEL (\x07) and ST (\x1b\) are handled.

Wizard "Test Connection" moved off the main thread: requests.get runs in a
daemon thread; result posted back via after(0, ...). Widget refs captured
before thread launch to prevent stale updates if user navigates away. Bare
except narrowed to TclError (destroyed-widget guard only).

Code quality: import os moved to module level in app.py; _read_raw_config()
helper extracted to deduplicate dual raw config.json reads; return type
annotations added to _get_view_class, _get_dashboard, and cfg property.

Tests: 11 new unit tests for _QueueWriter (RED -> GREEN on OSC-ST fix).

CLAUDE.md

@@ -92,7 +92,7 @@ Pass 2 builds `ok_disk_names` — the set of disk names that already match the s
 - `gui/app.py` — `ArmaModManagerApp` main window; manages view routing, config loading, thread-safe log queue, and background pipeline execution
 - `gui/wizard.py` — `SetupWizard` dialog shown on first launch when no `config.json` exists
 - `gui/_constants.py` — window dimensions, status color constants, file paths
-- `gui/_io.py` — `_QueueWriter` redirects stdout/stderr to a thread-safe queue so pipeline output streams into the Logs view
+- `gui/_io.py` — `_QueueWriter` redirects stdout/stderr to a thread-safe queue so pipeline output streams into the Logs view. `write()` strips ANSI/CSI escape codes and converts bare `\r` to `\n` before enqueuing, so `tqdm` progress output is legible in the textbox.
 
 **Views** (`gui/views/`): each inherits `BaseView`; `build()` runs once on creation, `refresh()` runs on each navigation:
 - `dashboard.py` — overview, status, quick stats
@@ -110,6 +110,8 @@ Pass 2 builds `ok_disk_names` — the set of disk names that already match the s
 
 **`run_tool` subprocess streaming:** Tool scripts are launched via `subprocess.Popen` (not `subprocess.run`) with `stdout=PIPE, stderr=STDOUT`, read line-by-line via `iter(proc.stdout.readline, "")`, and posted to the log queue immediately. Python's own output buffering is disabled with the `-u` flag and `PYTHONUNBUFFERED=1` in the environment — without these, output would batch inside the pipe and only appear when the script exits.
 
+**GUI threading model:** Every network or long-running operation runs in a `threading.Thread(daemon=True)` so the Tkinter event loop is never blocked. The only safe way to update widgets from a background thread is `self.after(0, callback)` — never touch widgets directly from a worker thread. `_poll_log` drains the entire log queue in one `after(80, ...)` tick and does a single batched `CTkTextbox.insert()` call rather than one per log entry, keeping the UI smooth even when `tqdm` emits many rapid updates during downloads. The wizard's "Test Connection" button follows the same pattern: `requests.get` runs in a daemon thread; the result is posted back via `self.after(0, ...)` with widget references captured *before* the thread starts, so stale references cannot update the wrong widgets if the user navigates away mid-request.
+
 ### GUI localization (`gui/locales.py`)
 
 All user-facing strings are centralised in `gui/locales.py`. Two languages are supported: English (`"en"`) and Vietnamese (`"vi"`).