refactor(gptel): lazy-load gptel-magit, rebind rewrite/context keys

- Replace use-package gptel-magit hook with autoloads via
  with-eval-after-load 'magit (loads gptel only on key press)
- Move org header defuns above use-package to fix load order
- Set gptel-include-reasoning to "*AI-Reasoning*" buffer
- Rebind rewrite to C-; a r, clear context to C-; a c
- Add test-ai-config-gptel-magit-lazy-loading.el (8 tests)
- Mark all ai-config cleanup items DONE in todo.org

1 files changed, 3 insertions, 3 deletions

diff --git a/todo.org b/todo.org
index e71def90..e4722093 100644
--- a/todo.org
+++ b/todo.org
@@ -173,9 +173,9 @@ Changed to ~"*AI-Reasoning*"~ — reasoning redirected to a separate buffer to
 keep conversations clean while remaining reviewable. Not re-sent as context
 (saves API tokens). Can be toggled per-session via gptel menu (~C-; a M~).
 
-**** ~gptel-magit~ loads on every magit open
-Hook ~(magit-mode . gptel-magit-install)~ runs every magit session even when
-AI commit messages aren't needed. Minor overhead.
+**** DONE ~gptel-magit~ loads on every magit open
+Replaced use-package hook with lazy autoloads via ~with-eval-after-load 'magit~.
+Keybindings wired up once when magit loads; gptel-magit only loads on key press.
 
 **** DONE Rewrite bound to ~&~ — unusual mnemonic
 Rewrite moved to ~C-; a r~, clear context moved to ~C-; a c~.