feat(extensions): add vundo/kubel/org-caldav/envrc/combobulate and more

Tier 1: org-caldav (CalDAV sync), envrc (direnv), kubel (K8s)
Tier 2: org-clock config, combobulate, vundo, breadcrumb, iedit
Tier 3: org-anki, org-ql, calfw, org-roam-ui, dirvish
Plus: citar/bibtex config, langtool grammar, org-ql search

packages.el

@@ -94,3 +94,26 @@
 ;; Git
 (package! git-link)
 
+;;; ============================================================
+;;; EXTENSIONS — Tier 1-3
+;;; ============================================================
+
+;; Tier 1 — High impact
+(package! kubel)
+(package! org-caldav)
+(package! envrc)
+
+;; Tier 2 — Quality of life
+(package! vundo)
+(package! iedit)
+(package! combobulate :recipe (:host github :repo "mickeynp/combobulate"))
+(package! breadcrumb :recipe (:host github :repo "joaotavora/breadcrumb"))
+
+;; Tier 3 — Supplementary
+(package! org-anki)
+(package! org-ql)
+(package! calfw)
+(package! calfw-org)
+(package! org-roam-ui)
+(package! dirvish)
+