feat(tui2): copy tui crate and normalize snapshots (#7833)

Introduce a full codex-tui source snapshot under the new codex-tui2
crate so viewport work can be replayed in isolation.

This change copies the entire codex-rs/tui/src tree into
codex-rs/tui2/src in one atomic step, rather than piecemeal, to keep
future diffs vs the original viewport bookmark easy to reason about.

The goal is for codex-tui2 to render identically to the existing TUI
behind the `features.tui2` flag while we gradually port the
viewport/history commits from the joshka/viewport bookmark onto this
forked tree.

While on this baseline change, we also ran the codex-tui2 snapshot test
suite and accepted all insta snapshots for the new crate, so the
snapshot files now use the codex-tui2 naming scheme and encode the
unmodified legacy TUI behavior. This keeps later viewport commits
focused on intentional behavior changes (and their snapshots) rather
than on mechanical snapshot renames.

codex-rs/tui2/src/slash_command.rs

@@ -0,0 +1,106 @@
+use strum::IntoEnumIterator;
+use strum_macros::AsRefStr;
+use strum_macros::EnumIter;
+use strum_macros::EnumString;
+use strum_macros::IntoStaticStr;
+
+/// Commands that can be invoked by starting a message with a leading slash.
+#[derive(
+    Debug, Clone, Copy, PartialEq, Eq, Hash, EnumString, EnumIter, AsRefStr, IntoStaticStr,
+)]
+#[strum(serialize_all = "kebab-case")]
+pub enum SlashCommand {
+    // DO NOT ALPHA-SORT! Enum order is presentation order in the popup, so
+    // more frequently used commands should be listed first.
+    Model,
+    Approvals,
+    Skills,
+    Review,
+    New,
+    Resume,
+    Init,
+    Compact,
+    Undo,
+    Diff,
+    Mention,
+    Status,
+    Mcp,
+    Logout,
+    Quit,
+    Exit,
+    Feedback,
+    Rollout,
+    TestApproval,
+}
+
+impl SlashCommand {
+    /// User-visible description shown in the popup.
+    pub fn description(self) -> &'static str {
+        match self {
+            SlashCommand::Feedback => "send logs to maintainers",
+            SlashCommand::New => "start a new chat during a conversation",
+            SlashCommand::Init => "create an AGENTS.md file with instructions for Codex",
+            SlashCommand::Compact => "summarize conversation to prevent hitting the context limit",
+            SlashCommand::Review => "review my current changes and find issues",
+            SlashCommand::Resume => "resume a saved chat",
+            SlashCommand::Undo => "ask Codex to undo a turn",
+            SlashCommand::Quit | SlashCommand::Exit => "exit Codex",
+            SlashCommand::Diff => "show git diff (including untracked files)",
+            SlashCommand::Mention => "mention a file",
+            SlashCommand::Skills => "use skills to improve how Codex performs specific tasks",
+            SlashCommand::Status => "show current session configuration and token usage",
+            SlashCommand::Model => "choose what model and reasoning effort to use",
+            SlashCommand::Approvals => "choose what Codex can do without approval",
+            SlashCommand::Mcp => "list configured MCP tools",
+            SlashCommand::Logout => "log out of Codex",
+            SlashCommand::Rollout => "print the rollout file path",
+            SlashCommand::TestApproval => "test approval request",
+        }
+    }
+
+    /// Command string without the leading '/'. Provided for compatibility with
+    /// existing code that expects a method named `command()`.
+    pub fn command(self) -> &'static str {
+        self.into()
+    }
+
+    /// Whether this command can be run while a task is in progress.
+    pub fn available_during_task(self) -> bool {
+        match self {
+            SlashCommand::New
+            | SlashCommand::Resume
+            | SlashCommand::Init
+            | SlashCommand::Compact
+            | SlashCommand::Undo
+            | SlashCommand::Model
+            | SlashCommand::Approvals
+            | SlashCommand::Review
+            | SlashCommand::Logout => false,
+            SlashCommand::Diff
+            | SlashCommand::Mention
+            | SlashCommand::Skills
+            | SlashCommand::Status
+            | SlashCommand::Mcp
+            | SlashCommand::Feedback
+            | SlashCommand::Quit
+            | SlashCommand::Exit => true,
+            SlashCommand::Rollout => true,
+            SlashCommand::TestApproval => true,
+        }
+    }
+
+    fn is_visible(self) -> bool {
+        match self {
+            SlashCommand::Rollout | SlashCommand::TestApproval => cfg!(debug_assertions),
+            _ => true,
+        }
+    }
+}
+
+/// Return all built-in commands in a Vec paired with their command string.
+pub fn built_in_slash_commands() -> Vec<(&'static str, SlashCommand)> {
+    SlashCommand::iter()
+        .filter(|command| command.is_visible())
+        .map(|c| (c.command(), c))
+        .collect()
+}