feat(_progress[spinner]): add Spinner, BuildTree, templates, and presets

why: The CLI needs an animated progress display during workspace builds.
A dedicated module keeps display logic decoupled from builder and load.
what:
- Add Spinner context manager with atexit cursor restore and non-TTY fallback
- Add BuildTree for tracking build state (session, windows, panes)
- Add scrolling output panel for before_script output lines
- Add PROGRESS_PRESETS (default, minimal, window, pane, verbose) with
  format_template using {session}, {window}, {bar}, {progress}, etc.
- Add render_bar() with marching indicator during before_script
- Add SUCCESS_TEMPLATE and format_success() for persistent completion line
- Add _SafeFormatMap, ANSI-aware truncation, dynamic terminal width refresh

Author: tony

src/tmuxp/_internal/colors.py

@@ -610,6 +610,7 @@ def get_color_mode(color_arg: str | None = None) -> ColorMode:
 # ANSI styling utilities (originally from click, via utils.py)
 
 _ansi_re = re.compile(r"\033\[[;?0-9]*[a-zA-Z]")
+ANSI_SEQ_RE = _ansi_re
 
 
 def strip_ansi(value: str) -> str:

src/tmuxp/cli/_colors.py

@@ -12,6 +12,7 @@
 import logging
 
 from tmuxp._internal.colors import (
+    ANSI_SEQ_RE,
     ColorMode,
     Colors,
     UnknownStyleColor,
@@ -25,6 +26,7 @@
 logger = logging.getLogger(__name__)
 
 __all__ = [
+    "ANSI_SEQ_RE",
     "ColorMode",
     "Colors",
     "UnknownStyleColor",