refactor(ai-vterm): rename Claude-specific names to a generic "agent"

I may add other terminal agents to this launcher (aider, an open-source LLM TUI), so the buffer prefix, the user knob, and the internal helpers shouldn't say "Claude". The module name (ai-vterm) and the `cj/ai-vterm-*` customs were already generic. This finishes the job:

- buffer prefix `claude [<basename>]` -> `agent [<basename>]` (the `defconst` and the matching display-buffer-alist regex move together)
- `cj/ai-vterm-claude-command` -> `cj/ai-vterm-agent-command` (the default still runs the `claude` CLI, with a docstring note on swapping it)
- `cj/--ai-vterm-claude-buffers` / `-displayed-claude-window` / `-reuse-existing-claude` -> `-agent-*`, and their test files renamed to match
- prose in the module commentary and docstrings, plus the matching test docstrings and buffer-name literals

`vterm-config.el` hardcodes the same buffer prefix in `cj/--vterm-toggle-buffer-p` (F12 excludes agent buffers from its candidate set), so that literal moved too. Collapsing it into the shared `cj/--ai-vterm-name-prefix` is a cleanup for another day.

After a reload, a project's buffer opens as `agent [foo]` instead of `claude [foo]`. Old buffers keep their names until killed. I also corrected two stale `eshell-vterm-config.el` references in ai-vterm.el docstrings (that module was split into `vterm-config.el`).

Two things keep saying "Claude": the `cj/ai-vterm-agent-command` default value (the actual CLI), and the "Claude Code" example in `vterm-config.el`'s cursor-restore docstring (a concrete TUI example, not branding).

90 tests pass. `make validate-modules` clean.

1 files changed, 7 insertions, 7 deletions

diff --git a/tests/test-ai-vterm--buffer-name.el b/tests/test-ai-vterm--buffer-name.el
index 95c673ba..2ebe91ee 100644
--- a/tests/test-ai-vterm--buffer-name.el
+++ b/tests/test-ai-vterm--buffer-name.el
@@ -2,7 +2,7 @@
 
 ;;; Commentary:
 ;; Tests for the buffer-name transform.  Given an absolute project
-;; directory, the helper returns "claude [<basename>]".  The naming pattern
+;; directory, the helper returns "agent [<basename>]".  The naming pattern
 ;; is what the display-buffer-alist rule keys on, so a regression here
 ;; silently breaks routing to the right side-window.
 
@@ -14,29 +14,29 @@
 (require 'ai-vterm)
 
 (ert-deftest test-ai-vterm--buffer-name-normal-project ()
-  "Normal: a typical project path yields claude [<basename>]."
+  "Normal: a typical project path yields agent [<basename>]."
   (should (equal (cj/--ai-vterm-buffer-name "/home/cjennings/projects/foo")
-                 "claude [foo]")))
+                 "agent [foo]")))
 
 (ert-deftest test-ai-vterm--buffer-name-trailing-slash ()
   "Boundary: trailing slash collapses before basename extraction."
   (should (equal (cj/--ai-vterm-buffer-name "/home/cjennings/projects/foo/")
-                 "claude [foo]")))
+                 "agent [foo]")))
 
 (ert-deftest test-ai-vterm--buffer-name-dot-prefix-dir ()
   "Boundary: dot-prefix dirs (.emacs.d) preserve the dot in the basename."
   (should (equal (cj/--ai-vterm-buffer-name "/home/cjennings/.emacs.d")
-                 "claude [.emacs.d]")))
+                 "agent [.emacs.d]")))
 
 (ert-deftest test-ai-vterm--buffer-name-space-in-basename ()
   "Boundary: a space in the basename round-trips into the buffer name."
   (should (equal (cj/--ai-vterm-buffer-name "/tmp/my work")
-                 "claude [my work]")))
+                 "agent [my work]")))
 
 (ert-deftest test-ai-vterm--buffer-name-deeply-nested ()
   "Normal: only the last path component is used."
   (should (equal (cj/--ai-vterm-buffer-name "/a/b/c/d/e/leaf")
-                 "claude [leaf]")))
+                 "agent [leaf]")))
 
 (provide 'test-ai-vterm--buffer-name)
 ;;; test-ai-vterm--buffer-name.el ends here