fix(docs): correct two broken intra-doc links

The CI runs `cargo doc --workspace --no-deps` with
`RUSTDOCFLAGS=-Dwarnings`. Two doc-comment links broke the
build:

* `commands/session.rs::prune` referenced
  `[\`SessionManager::prune_sessions_older_than\`]` which
  rustdoc tries to resolve as an item in scope. Without
  importing `SessionManager` into the doc-comment scope, the
  link was unresolvable. Fix by qualifying with the full
  module path: `[\`crate::session_manager::SessionManager::…\`]`.
* `config.rs::max_subagents` had a free-form `[subagents]`
  reference that rustdoc parsed as an intra-doc link. Wrap it
  in backticks so it renders as inline code instead.

No code change. Pure rustdoc hygiene; CI gate passes again.

crates/tui/src/commands/session.rs

@@ -208,9 +208,9 @@ pub fn sessions(app: &mut App, arg: Option<&str>) -> CommandResult {
 
 /// Prune persisted sessions older than `<days>` from
 /// `~/.deepseek/sessions/`. Wraps
-/// [`SessionManager::prune_sessions_older_than`] so users can run a
-/// safe cleanup without leaving the TUI. Skips the checkpoint
-/// subdirectory (the helper guarantees that already).
+/// [`crate::session_manager::SessionManager::prune_sessions_older_than`]
+/// so users can run a safe cleanup without leaving the TUI. Skips
+/// the checkpoint subdirectory (the helper guarantees that already).
 fn prune(_app: &mut App, days_arg: Option<&str>) -> CommandResult {
     let days_str = match days_arg {
         Some(s) => s,

crates/tui/src/config.rs

@@ -1296,8 +1296,8 @@ impl Config {
     }
 
     /// Return the maximum number of concurrent sub-agents.
-    /// Checks [subagents] max_concurrent first, then top-level max_subagents,
-    /// then falls back to DEFAULT_MAX_SUBAGENTS.
+    /// Checks `[subagents] max_concurrent` first, then top-level `max_subagents`,
+    /// then falls back to `DEFAULT_MAX_SUBAGENTS`.
     #[must_use]
     pub fn max_subagents(&self) -> usize {
         // Check [subagents] max_concurrent first