refactor: modularize auth transport and markdown

- Split auth into focused package modules for agent keys, file keys,
  signing, and post-quantum transport helpers while keeping the public
  browser_cli.auth import surface intact.
- Move transport encoding internals into a package with separate codec and
  binary-hoisting helpers, preserving browser_cli.transport compatibility.
- Extract remote TCP auth/socket helpers and serve challenge setup out of the
  runtime paths to make connection handling easier to reason about.
- Move the extension markdown extractor into a dedicated content/markdown
  folder with separate root selection, code normalization, renderer, and utils.
- Centralize CLI Rich rendering helpers for tab/window tree and table output,
  and add rendering tests for the shared builders.
- Remove local typing ignores in SDK/decorator/script plumbing and bump the
  package and extension version to 0.15.3.

browser_cli/commands/windows.py

@@ -1,33 +1,21 @@
 import click
 from browser_cli.commands import client_from_ctx, handle_errors
-from browser_cli.commands.rendering import print_tree, tab_tree_label, tree_title_limit, tree_url_limit
+from browser_cli.commands.rendering import build_windows_tree, print_table_rows, print_tree
 from rich.console import Console
-from rich.table import Table
-from rich.tree import Tree
 
 console = Console()
 
 def _print_windows(windows: list[dict], *, show_browser: bool = False) -> None:
-  if not windows:
-    console.print("[yellow]No windows found[/yellow]")
-    return
-  table = Table(show_header=True, header_style="bold cyan")
+  columns = []
   if show_browser:
-    table.add_column("Browser")
-  table.add_column("ID", style="dim", no_wrap=True)
-  table.add_column("Alias", width=20)
-  table.add_column("Tabs", width=6)
-  table.add_column("State", width=12)
-  for w in windows:
-    row = [
-      w.get("browser", "") if show_browser else None,
-      str(w.get("id", "")),
-      w.get("alias") or "",
-      str(w.get("tabCount", "")),
-      w.get("state") or "",
-    ]
-    table.add_row(*[value for value in row if value is not None])
-  console.print(table)
+    columns.append(("Browser", lambda window: window.get("browser", "")))
+  columns.extend([
+    ("ID", lambda window: window.get("id", "")),
+    ("Alias", lambda window: window.get("alias") or ""),
+    ("Tabs", lambda window: window.get("tabCount", "")),
+    ("State", lambda window: window.get("state") or ""),
+  ])
+  print_table_rows(windows, columns, console=console, empty_message="[yellow]No windows found[/yellow]")
 
 @click.group("windows")
 def windows_group():
@@ -45,21 +33,7 @@ def windows_list():
 def windows_tree():
   """Show windows and their tabs as a tree."""
   client = client_from_ctx()
-  windows = client.windows.list()
-  tabs = client.tabs.list()
-  root = Tree("[bold]Windows[/bold]")
-  title_limit = tree_title_limit(console=console, show_browser=any("browser" in w for w in windows), show_urls=True)
-  url_limit = tree_url_limit(title_limit, console=console)
-  for w in sorted(windows, key=lambda item: (item.get("browser", ""), item.get("id", 0))):
-    wid = w.get("id")
-    label = f"Window {wid}"
-    if w.get("alias"):
-      label += f" ({w['alias']})"
-    if w.get("browser"):
-      label = f"{w['browser']}: " + label
-    node = root.add(label)
-    for tab in sorted([t for t in tabs if t.window_id == wid and (not w.get("browser") or t.browser == w.get("browser"))], key=lambda t: getattr(t, "index", 0)):
-      node.add(tab_tree_label(tab, title_limit=title_limit, show_urls=True, url_limit=url_limit))
+  root = build_windows_tree(client.windows.list(), client.tabs.list(), console=console)
   print_tree(root, console=console)
 
 @windows_group.command("rename")