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

config.el

@@ -1724,3 +1724,172 @@ current frame."
 (after! projectile
   (dolist (dir '("node_modules" "__pycache__" ".terraform" "vendor"))
     (add-to-list 'projectile-globally-ignored-directories dir)))
+
+
+;;; ============================================================
+;;; EXTENSIONS — Tier 1-3 + BibTeX
+;;; ============================================================
+
+;;; --- Tier 1: High impact ---
+
+;; org-caldav — CalDAV sync for org
+(use-package! org-caldav
+  :commands org-caldav-sync
+  :config
+  (setq org-caldav-url "https://cal.apps.sukany.cz/dav/calendars/martin@sukany.cz"
+        org-caldav-calendar-id "Martin"
+        org-caldav-inbox "~/org/caldav-inbox.org"
+        org-caldav-files '("~/org/personal.org" "~/org/work.org")
+        org-caldav-sync-direction 'twoway))
+(map! :leader "o c" #'org-caldav-sync)
+
+;; envrc — direnv integration
+(use-package! envrc
+  :hook (after-init . envrc-global-mode))
+
+;; embark — custom prompter (already installed by Doom vertico module)
+(after! embark
+  (setq embark-prompter #'embark-keymap-prompter))
+
+;; wgrep — already installed by Doom vertico module, just configure
+(after! wgrep
+  (setq wgrep-auto-save-buffer t))
+
+;; kubel — Kubernetes management
+(use-package! kubel
+  :commands kubel
+  :config
+  (map! :map kubel-mode-map
+        :n "g" #'kubel-get-resource-details
+        :n "E" #'kubel-exec-pod
+        :n "l" #'kubel-get-pod-logs
+        :n "d" #'kubel-describe-resource
+        :n "D" #'kubel-delete-resource))
+(map! :leader "o k" #'kubel)
+
+;;; --- Tier 2: Quality of life ---
+
+;; org-clock — time tracking (built into org, just configure)
+(after! org
+  (setq org-clock-persist 'history
+        org-clock-in-resume t
+        org-clock-out-remove-zero-time-clocks t
+        org-clock-report-include-clocking-task t
+        org-duration-format 'h:mm)
+  (org-clock-persistence-insinuate)
+  (map! :map org-mode-map
+        :localleader
+        "C i" #'org-clock-in
+        "C o" #'org-clock-out
+        "C r" #'org-clock-report
+        "C d" #'org-clock-display))
+
+;; combobulate — tree-sitter structural editing
+(use-package! combobulate
+  :hook ((python-mode . combobulate-mode)
+         (python-ts-mode . combobulate-mode)
+         (go-mode . combobulate-mode)
+         (go-ts-mode . combobulate-mode)
+         (js-mode . combobulate-mode)
+         (typescript-mode . combobulate-mode))
+  :config
+  (map! :map combobulate-mode-map
+        :n "C-M-n" #'combobulate-navigate-next
+        :n "C-M-p" #'combobulate-navigate-previous
+        :n "C-M-u" #'combobulate-navigate-up
+        :n "C-M-d" #'combobulate-navigate-down))
+
+;; iedit — edit multiple occurrences
+(use-package! iedit
+  :commands iedit-mode)
+(map! :leader "s e" #'iedit-mode)
+
+;; vundo — visual undo tree
+(use-package! vundo
+  :commands vundo
+  :config (setq vundo-glyph-alist vundo-unicode-symbols))
+(map! :leader "u" #'vundo)
+
+;; breadcrumb — context in header-line
+(use-package! breadcrumb
+  :hook ((prog-mode . breadcrumb-local-mode)
+         (cperl-mode . breadcrumb-local-mode)))
+
+;;; --- Tier 3: Supplementary ---
+
+;; org-anki — Anki flashcards from org
+(use-package! org-anki
+  :commands (org-anki-sync-entry org-anki-sync-all org-anki-delete-entry)
+  :config
+  (setq org-anki-default-deck "Emacs")
+  (map! :map org-mode-map
+        :localleader
+        "A s" #'org-anki-sync-entry
+        "A S" #'org-anki-sync-all
+        "A d" #'org-anki-delete-entry))
+
+;; org-ql — query language for org
+(use-package! org-ql
+  :commands (org-ql-search org-ql-view org-ql-find)
+  :config
+  (map! :leader
+        "s q" #'org-ql-search
+        "s Q" #'org-ql-view))
+
+;; calfw — visual calendar
+(use-package! calfw
+  :commands cfw:open-org-calendar)
+(use-package! calfw-org
+  :after calfw
+  :commands cfw:open-org-calendar)
+(map! :leader "o C" #'cfw:open-org-calendar)
+
+;; org-roam-ui — visual graph for org-roam
+(use-package! org-roam-ui
+  :after org-roam
+  :commands org-roam-ui-mode
+  :config
+  (setq org-roam-ui-sync-theme t
+        org-roam-ui-follow t
+        org-roam-ui-update-on-save t))
+(map! :leader "n r u" #'org-roam-ui-mode)
+
+;; dirvish — modern dired replacement
+(use-package! dirvish
+  :init (dirvish-override-dired-mode)
+  :config
+  (setq dirvish-mode-line-format '(:left (sort symlink) :right (omit yank index))
+        dirvish-attributes '(vc-state subtree-state nerd-icons collapse git-msg file-time file-size)
+        dirvish-side-width 35)
+  (map! :map dirvish-mode-map
+        :n "q" #'dirvish-quit
+        :n "h" #'dired-up-directory
+        :n "l" #'dired-find-file
+        :n "s" #'dirvish-quicksort
+        :n "S" #'dirvish-setup-menu
+        :n "TAB" #'dirvish-subtree-toggle
+        :n "M-f" #'dirvish-history-go-forward
+        :n "M-b" #'dirvish-history-go-backward))
+
+;;; --- BibTeX / Citar (installed by Doom biblio module) ---
+
+(after! citar
+  (setq citar-bibliography '("~/org/references.bib")
+        citar-notes-paths '("~/org/notes/")
+        citar-library-paths '("~/org/papers/"))
+  (map! :leader
+        "b b" #'citar-open
+        "b i" #'citar-insert-citation
+        "b n" #'citar-open-notes
+        "b r" #'citar-refresh))
+
+;;; --- Grammar check (LanguageTool, installed by Doom grammar module) ---
+
+(after! langtool
+  (setq langtool-language-tool-jar
+        (expand-file-name "~/languagetool/languagetool-commandline.jar")
+        langtool-default-language "cs"
+        langtool-mother-tongue "cs"))
+(map! :leader
+      "t g" #'langtool-check
+      "t G" #'langtool-check-done)