feat: show line change counts in diff tabs

TODO.md

@@ -1,22 +1,4 @@
-- [x] jj conflict resolution with ui akin to the diff viewer
-- [x] make selecting a file in the diff view file picker focus the after buffer instead of the before buffer
-- [x] improve the lsp hover floating window:
-	- it should be taller
-- [x] add support for zig syntax highlighting
-- [x] add the `*` action from vim on word to highlights and searches in buffer in one action.
-- [x] diff view: improve word-diff highlighting
-- [x] diff view: show the function/class context that a change hunk belongs to.
-    - inline scope labels with sticky continuation, chosen before implementation
-    - each side uses its own syntax tree; scope changes within a hunk get separate labels
-- [x] diff view: annotate folder with checkmark if all items under given folder has been checked AND the folder is collapsed.
-- [x] diff view: automatically detect changes and update the view when relevant bookmarks move change ids (regards bookmark-based diff view; i.e., user selected at least one bookmark in the before/after picker)
-- [x] action to scroll viewport without having to move the cursor (like vim's `ctrl+e|u`).
-- [x] scroll viewport action (`ctrl+u|d`) scroll distance should be configurable.
-- [x] file picker file search should also be fuzzy (we should be able to use the same fuzzy implemented for diff view search, i believe)
-- [x] diff view: labels are currently attached also when scrolling the view port horizontally (such that e.g. a function name is not fully visible in the viewport), which is good, but it currently attaches at that line, thus pushing down the function by one line, which causes a one-line jump when scrolling horizontally.
-    - horizontal labels overlay the row above the declaration without shifting source rows; hide the label when it would cover the pane border or a visible declaration name.
-    - sticky context retains the immediately adjacent declaration as numbered source when its name fits; only use the label after it scrolls farther out.
-- [ ] diff view: add change count (added and removed) to the tab name. format could be something like `Diff · <changes> · <buffer name>`.
+- [x] diff view: add change count (added and removed) to the tab name. format could be something like `Diff · <changes> · <buffer name>`.
 - [ ] diff view: github integration (code review) - add comments on a pr, add review comments at specific lines of files, request changes, approve pr, etc.
 - [ ] diff view: local review comments (same features as for github reviews) that allows review of local changes to deliver specific reviews to ai agents used for coding.
 	- design question: would this require a server that the agent can interact with, or would local review files be fine? don't want to use server client stuff, if it would be easier and better to just use local files.