fix(git-status): address #537 review (docker workspaces, gone upstream, in-flight reset, docs)

- never inspect a repository at or inside a Docker case workspace (walk-up, scan, diff route): git would run its clean filters on the host
- a branch whose upstream was deleted and pruned reports upstreamGone and falls back to commits on no remote, instead of green
- turning the setting off during a poll releases the in-flight flag
- log.showSignature=false; reword the docs: clean filters still run
- CLAUDE.md frontend load order, changeset names git-diff
- discovery reads a bounded, sorted directory listing; leading-dash paths allowed; diff 500 redacts credentials
- keyboard focus survives the poll re-render; panel stays on screen on narrow viewports; aria-expanded visible on light skins

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JrzFKEdBLwVfu6ev2ZscJS

src/web/public/styles.css

@@ -19316,16 +19316,18 @@ html .toolbar .btn-git-status.git-status--conflict {
   border-color: rgba(229, 83, 75, 0.5);
 }
 
-.btn-git-status[aria-expanded='true'] {
-  background: rgba(255, 255, 255, 0.12);
+html .toolbar .btn-git-status[aria-expanded='true'] {
+  background: color-mix(in srgb, currentColor 16%, transparent);
 }
 
 /* Same look as the Files window. Default spot is just left of it so both can be open. */
 .git-status-panel {
   position: fixed;
   top: calc(var(--header-height) + 10px);
-  right: 320px;
+  /* Just left of the Files window; on a narrow viewport slide right so the left edge never leaves the screen. */
+  right: clamp(8px, calc(100vw - 388px), 320px);
   width: 380px;
+  max-width: calc(100vw - 16px);
   height: calc(100vh - var(--header-height) - var(--toolbar-height) - 40px);
   height: calc(100dvh - var(--header-height) - var(--toolbar-height) - 40px);
   max-height: 600px;