Line up the feed sidebar

Every row reserves the chevron slot, so artwork and titles share one
column instead of stepping left when a feed has no children. Children
keep a single icon size and read as nested from the indent alone. Labels
stack on one line-height, and the unread count has a min-width so a
three-digit feed doesn't shove its own title.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AdXho5tTkjFLeUXKbEjKBh

PROGRESS.md

@@ -56,6 +56,20 @@ and until now nothing set them.
 
 ---
 
+## 2026-09-10 — Sidebar alignment
+
+The feed list had four different left edges: a row with no children skipped the chevron entirely, so
+its artwork sat a chevron-width left of a folder's; children then used a different indent *and* a
+smaller icon. Nothing lined up with anything.
+
+Every row now reserves the chevron slot whether or not it opens (an empty one is
+`pointer-events:none`, so the click falls through to the row), all artwork is one size, and nesting
+reads from the indent alone. Both label lines are `display:block` on a shared line-height instead of
+an inline baseline, and the unread count has a `min-width` so three-digit feeds don't shove the
+title. Rows came out shorter, so more feeds fit without scrolling.
+
+---
+
 ## 2026-09-10 — An item's picture
 
 An item's artwork now resolves in order of how deliberate the source is: `itunes:image`, then Media