Add GUI desktop application

- Add gui/ package: CustomTkinter app with dashboard, mods, tools, logs,
  and settings views; first-run SetupWizard for config.json generation
- Add gui.py root entry point (calls gui.run_app())
- Add selection.json for GUI selection state persistence
- Add customtkinter to requirements.txt
- Fix link_mods.py minor issues surfaced during GUI integration
- Add modlist_html/Test_Preset_A.html and Test_Preset_B.html as example inputs
- Update README.md: add GUI prerequisites, gui.py script section, gui/ folder
  structure, customtkinter to prerequisites table
- Update CLAUDE.md: add python gui.py to common commands, document GUI package
  architecture and views

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gui/views/logs.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import customtkinter as ctk
+
+from gui._constants import COLOR_ERROR
+from gui.views.base import BaseView
+
+if TYPE_CHECKING:
+    from gui.app import ArmaModManagerApp
+
+
+class LogsView(BaseView):
+    """
+    Monospace textbox showing captured stdout/stderr from pipeline and tools.
+
+    The app's poll loop appends text by calling append() directly on this view.
+    Log content persists across navigation — the textbox is built once in build()
+    and never recreated.
+    """
+
+    def build(self) -> None:
+        self.grid_columnconfigure(0, weight=1)
+        self.grid_rowconfigure(1, weight=1)
+
+        # ── Header ────────────────────────────────────────────────────────────
+        hdr = ctk.CTkFrame(self, fg_color="transparent")
+        hdr.grid(row=0, column=0, sticky="ew", padx=24, pady=(20, 8))
+        ctk.CTkLabel(hdr, text="Logs",
+                     font=ctk.CTkFont(size=22, weight="bold")).pack(side="left")
+
+        btn_row = ctk.CTkFrame(hdr, fg_color="transparent")
+        btn_row.pack(side="right")
+        ctk.CTkButton(btn_row, text="Copy", width=72,
+                      command=self._copy).pack(side="left", padx=4)
+        ctk.CTkButton(btn_row, text="Clear", width=72,
+                      fg_color=COLOR_ERROR, hover_color="#c62828",
+                      command=self._clear).pack(side="left")
+
+        # ── Log textbox (persistent) ──────────────────────────────────────────
+        self._log_box = ctk.CTkTextbox(
+            self, state="disabled",
+            font=ctk.CTkFont(family="Consolas", size=12))
+        self._log_box.grid(row=1, column=0, sticky="nsew", padx=24, pady=(0, 12))
+
+    def append(self, text: str) -> None:
+        """Thread-safe-ish: called from the app's after() poll loop (main thread)."""
+        try:
+            self._log_box.configure(state="normal")
+            self._log_box.insert("end", text)
+            self._log_box.see("end")
+            self._log_box.configure(state="disabled")
+        except Exception:
+            pass
+
+    def _copy(self) -> None:
+        self.clipboard_clear()
+        self.clipboard_append(self._log_box.get("1.0", "end"))
+
+    def _clear(self) -> None:
+        self._log_box.configure(state="normal")
+        self._log_box.delete("1.0", "end")
+        self._log_box.configure(state="disabled")