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--display-rule.el b/tests/test-ai-vterm--display-rule.el
index af481eb3..15d270e2 100644
--- a/tests/test-ai-vterm--display-rule.el
+++ b/tests/test-ai-vterm--display-rule.el
@@ -2,7 +2,7 @@
 
 ;;; Commentary:
 ;; The module installs a `display-buffer-alist' entry routing buffers
-;; whose names match "\\`claude \\[" to a right-side window.  These
+;; whose names match "\\`agent \\[" to a right-side window.  These
 ;; tests verify the rule reaches the right side and ignores buffers
 ;; that don't match the prefix.
 
@@ -26,13 +26,13 @@
      (let ((display-buffer-alist (cj/--ai-vterm-display-rule-list)))
        ,@body)))
 
-(ert-deftest test-ai-vterm--display-rule-routes-claude-buffer-to-right ()
-  "Normal: a buffer named \"claude [foo]\" lands in a window to the right.
+(ert-deftest test-ai-vterm--display-rule-routes-agent-buffer-to-right ()
+  "Normal: a buffer named \"agent [foo]\" lands in a window to the right.
 
 The rule uses `display-buffer-in-direction' with `(direction . right)',
 which splits the current window so the new window's left edge sits at
 a positive column.  The buffer winds up in that new window."
-  (let ((name "claude [display-rule-test]"))
+  (let ((name "agent [display-rule-test]"))
     (test-ai-vterm--cleanup name)
     (unwind-protect
         (test-ai-vterm--with-clean-frame
@@ -43,7 +43,7 @@ a positive column.  The buffer winds up in that new window."
       (test-ai-vterm--cleanup name))))
 
 (ert-deftest test-ai-vterm--display-rule-skips-non-matching-buffer ()
-  "Boundary: a buffer not named \"claude [...]\" does not match the rule.
+  "Boundary: a buffer not named \"agent [...]\" does not match the rule.
 
 The rule's regex doesn't fire, so `display-buffer' falls back to the
 default action -- reuse the current window -- and no rightward split
@@ -59,8 +59,8 @@ occurs."
       (test-ai-vterm--cleanup name))))
 
 (ert-deftest test-ai-vterm--display-rule-prefix-not-substring ()
-  "Boundary: \"foo claude [bar]\" does not match -- the rule anchors at start."
-  (let ((name "foo claude [substring-test]"))
+  "Boundary: \"foo agent [bar]\" does not match -- the rule anchors at start."
+  (let ((name "foo agent [substring-test]"))
     (test-ai-vterm--cleanup name)
     (unwind-protect
         (test-ai-vterm--with-clean-frame