test: add 86 new tests, fix 3 production bugs, fix 8 stale tests

New test coverage (86 tests across 7 files):
- custom-case: 43 tests (title-case-region, upcase-dwim, downcase-dwim)
- custom-datetime: 10 tests (all insert methods with mocked time)
- config-utilities: 11 tests (format-build-time type branching)
- org-capture-config: 22 tests (date-prefix + event-content)

Production bugs found and fixed:
- custom-case: title-case-region crashes on whitespace/punctuation-only input
  (char-after returns nil when no word chars found)
- org-capture-config: browser branch missing empty-string guard on :initial
  plist value, producing stray newline in capture output
- mousetrap-mode: keymap never registered in minor-mode-map-alist, so mode
  was silently not blocking any mouse events. Now pushes/removes on toggle.

Additional fixes:
- local-repository: fix cons cell syntax bug in localrepo-initialize
  (was calling vars as functions instead of using cons)
- dupre-theme tests: update rainbow-delimiter color expectations
- mousetrap tests: update dashboard profile (primary-click → scroll+primary)
- music completion test: bind completion-ignore-case to prevent pollution
- Delete redundant interactive recording test (duplicate of ERT version)

Refactoring:
- org-capture-config: extract cj/org-capture--date-prefix pure function
  from cj/org-capture-format-event-headline for testability

Test checklist: todo.org updated to [11/25], removed untestable modules

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/test-dupre-theme.el b/tests/test-dupre-theme.el
index d044cd80..32fa437e 100644
--- a/tests/test-dupre-theme.el
+++ b/tests/test-dupre-theme.el
@@ -176,16 +176,16 @@
 ;;; Rainbow-delimiters tests (skip if package not available)
 
 (ert-deftest dupre-theme-rainbow-depth-1 ()
-  "Rainbow depth 1 should use yellow."
+  "Rainbow depth 1 should use blue."
   (skip-unless (require 'rainbow-delimiters nil t))
   (load-theme 'dupre t)
-  (should (string= (face-attribute 'rainbow-delimiters-depth-1-face :foreground) "#d7af5f")))
+  (should (string= (face-attribute 'rainbow-delimiters-depth-1-face :foreground) "#67809c")))
 
 (ert-deftest dupre-theme-rainbow-depth-2 ()
-  "Rainbow depth 2 should use blue."
+  "Rainbow depth 2 should use gray+2."
   (skip-unless (require 'rainbow-delimiters nil t))
   (load-theme 'dupre t)
-  (should (string= (face-attribute 'rainbow-delimiters-depth-2-face :foreground) "#67809c")))
+  (should (string= (face-attribute 'rainbow-delimiters-depth-2-face :foreground) "#d0cbc0")))
 
 ;;; Error/warning face tests