fix(ai-vterm): direction-based display + per-project tmux session names

Two post-ship issues blocked practical use of the new launcher.

The display rule used `display-buffer-in-side-window` with `(dedicated . t)`. Side-window dedication caused `set-window-buffer` to error during `buffer-move` (C-M-arrows), which left a half-finished swap with both sides showing the claude buffer. Then `switch-to-buffer` on a non-claude buffer in that dedicated window split instead of replacing.

I rewrote the rule as `display-buffer-reuse-window -> display-buffer-use-some-window -> display-buffer-in-direction (right)`. The resulting window is ordinary, not dedicated, so swap and replace work normally. I also narrowed `vterm-toggle`'s broad lambda (which matches any vterm-mode buffer) to exclude `claude [` buffers. Otherwise vterm-toggle's `:defer` made it install last and capture our buffers first with its own bottom-split + dedicated treatment.

The tmux side: vterm's auto-launch hook ran a bare `tmux\n`, so each session got an auto-named one. After an Emacs crash the tmux session would survive but I couldn't find it. A second F9 just spawned another. The launcher now sends `tmux new-session -A -s <basename> -c <dir> '<claude>; exec bash'`. The `-A` reattaches to a same-named session if it already exists. The `exec bash` keeps the tmux window alive if claude itself exits. A `cj/--ai-vterm-suppress-tmux` flag tells the existing vterm hook to skip its bare tmux step so the named launch runs instead.

11 new tests across 2 files cover the session-name and launch-command helpers. I updated tests for show-or-create and the display rule. All 34 ai-vterm tests are green.

1 files changed, 5 insertions, 3 deletions

diff --git a/tests/test-ai-vterm--show-or-create.el b/tests/test-ai-vterm--show-or-create.el
index 28e0faeb..3faf5f03 100644
--- a/tests/test-ai-vterm--show-or-create.el
+++ b/tests/test-ai-vterm--show-or-create.el
@@ -57,7 +57,7 @@ VARS is a plist of capture variable names: :calls, :strings, :returns,
     (kill-buffer name)))
 
 (ert-deftest test-ai-vterm--show-or-create-creates-when-buffer-missing ()
-  "Normal: no existing buffer -> vterm called once, claude cmd sent."
+  "Normal: no existing buffer -> vterm called once, launch cmd sent."
   (let ((name "claude [normal-create-test]"))
     (test-ai-vterm--cleanup name)
     (unwind-protect
@@ -65,7 +65,8 @@ VARS is a plist of capture variable names: :calls, :strings, :returns,
                                          :returns returns :default-dir ddir)
           (cj/--ai-vterm-show-or-create "/tmp/some-project" name)
           (should (equal calls (list name)))
-          (should (equal strings (list cj/ai-vterm-claude-command)))
+          (should (equal strings
+                         (list (cj/--ai-vterm-launch-command "/tmp/some-project"))))
           (should (= returns 1))
           (should (equal ddir "/tmp/some-project")))
       (test-ai-vterm--cleanup name))))
@@ -98,7 +99,8 @@ VARS is a plist of capture variable names: :calls, :strings, :returns,
                                              :returns returns :default-dir _ddir)
               (cj/--ai-vterm-show-or-create "/tmp/dead" name)
               (should (equal calls (list name)))
-              (should (equal strings (list cj/ai-vterm-claude-command)))
+              (should (equal strings
+                             (list (cj/--ai-vterm-launch-command "/tmp/dead"))))
               (should (= returns 1))
               (should-not (buffer-live-p stale)))))
       (test-ai-vterm--cleanup name))))