feat: gate XDG and PATH behind overrides toggle

Wrapped the XDG variables and PATH setup in config.fish with the C3 overrides toggle so users can fully opt out. Updated the documentation (07-customization.md, 02-path-setup.md, README.md) to reflect this. Also added a Home link to the 404 page and removed a leftover test_sidebar.js file.

docs/fish-config.md

@@ -310,6 +310,8 @@ shadowing system-installed Rust tools.
 
 NOTE: While these directories are merged with your system's existing `$PATH` values, any executables in the prepended directories above will override (shadow) system binaries of the same name.
 
+TIP: This standard PATH setup is gated behind the opinionated component overrides toggle. If you prefer to manage your PATH completely manually, you can disable it by setting `__fish_config_op_overrides` to `0` (or toggle it off in the `config-settings` menu).
+
 ---
 
 # 3. KEY BINDINGS
@@ -2720,6 +2722,8 @@ all of them.
     Override                  What it replaces or sets
     ───────────────────────────────────────────────────────────────────────────
     Vi mode                   fish_vi_key_bindings replaces default Emacs mode
+    XDG variables             Sets global XDG Base Directory variables
+    PATH setup                Prepends custom bin directories to the PATH
     exit → smart_exit         exit wrapper that captures scrollback before closing
     PAGER=ov                  ov used by git, man, and all $PAGER-aware tools
     MANPAGER=bat pipeline     man pages rendered with syntax highlighting

docs/manual/02-path-setup.md

@@ -26,4 +26,6 @@ shadowing system-installed Rust tools.
 
 NOTE: While these directories are merged with your system's existing `$PATH` values, any executables in the prepended directories above will override (shadow) system binaries of the same name.
 
+TIP: This standard PATH setup is gated behind the opinionated component overrides toggle. If you prefer to manage your PATH completely manually, you can disable it by setting `__fish_config_op_overrides` to `0` (or toggle it off in the `config-settings` menu).
+
 ---

docs/manual/07-customization.md

@@ -219,6 +219,8 @@ all of them.
     Override                  What it replaces or sets
     ───────────────────────────────────────────────────────────────────────────
     Vi mode                   fish_vi_key_bindings replaces default Emacs mode
+    XDG variables             Sets global XDG Base Directory variables
+    PATH setup                Prepends custom bin directories to the PATH
     exit → smart_exit         exit wrapper that captures scrollback before closing
     PAGER=ov                  ov used by git, man, and all $PAGER-aware tools
     MANPAGER=bat pipeline     man pages rendered with syntax highlighting

docs/manual/404.md

@@ -9,6 +9,7 @@ hero:
 ---
 
 <CardGrid>
+  <LinkCard title="Home" description="Return to the main manual page" href="/" />
   <LinkCard title="Installation" description="Set up the configuration" href="/09-installation/" />
   <LinkCard title="Troubleshooting" description="Fix common issues" href="/11-troubleshooting/" />
   <LinkCard title="Function Reference" description="Browse all functions" href="/05-functions/" />