macos: pixel attachments, live theming, and a signed app

The AppKit shell now draws what the core renders, follows the theme without a
relaunch, and builds into something you can hand to someone.

- Pixel attachments. Surface.images was dropped on the floor here, so a PDF
  pane showed nothing at all: native_images is now set, pardes_image_s carries
  the geometry the core already clipped, and PardesView keeps one CGImage per
  (serial, page, revision) so scrolling costs a draw and not a decode. Image
  panes get real pixels instead of the petscii fallback.

- Themes take hold live. pardes_tick never advanced the chrome animation, so
  every tagline kept the previous theme's colours until the next launch and
  the 16 ms re-pump spun for the rest of the session. pardes_theme_bg retires
  the hand-agreed #121212 and drives the window background and the titlebar
  appearance; a theme with no background of its own now gets a transparent
  window over an NSVisualEffectView.

- The cell snaps to whole DEVICE pixels rather than whole points. Monaco
  advances 8.4014pt at 14, so ceiling to 9 spaced every column 7.1% wider than
  the face was drawn for.

- The dial is one notch per 10 degrees instead of 20, and a release keeps
  turning in proportion to how hard it was thrown -- ramping up from zero at
  the floor, so a slow twist coasts not a little but not at all.

- A file dropped on the grid is a click plus Look, so it opens beside the pane
  it was dropped on. No drop concept was added to the core.

- The titlebar follows the focused pane: proxy icon, filename, and the dirty
  dot. File.saved_revision is the watermark that last one needed.

- Config (SPC f c) prints the resolved startup config path.

- build.zig assembles, signs and packages the bundle itself; build-app.sh is
  gone. -Dmacos-identity= takes a Developer ID, macos-dmg makes the image, and
  the icon is Glenda.

1 files changed, 20 insertions, 20 deletions

diff --git a/test/snapshots/leader.golden b/test/snapshots/leader.golden
index 74719f13..d58e8d6c 100644
--- a/test/snapshots/leader.golden
+++ b/test/snapshots/leader.golden
@@ -193,16 +193,16 @@
 |     6 SPC c d   Delcol
 |     7 SPC c n   Newcol          topbar
 |     8 SPC d     Del
-|     9 SPC f f   Find            topbar
-|    10 SPC f g   Grep            topbar
-|    11 SPC f n   New             topbar
-|    12 SPC f s   Save
-|    13 SPC h t   Tutor           topbar
-|    14 SPC j i   Forward         C-i
-|    15 SPC j j   Last
-|    16 SPC j l   Jumplist
-|    17 SPC j o   Back            C-o
-|    18 SPC k     Kill            topbar
+|     9 SPC f c   Config
+|    10 SPC f f   Find            topbar
+|    11 SPC f g   Grep            topbar
+|    12 SPC f n   New             topbar
+|    13 SPC f s   Save
+|    14 SPC h t   Tutor           topbar
+|    15 SPC j i   Forward         C-i
+|    16 SPC j j   Last
+|    17 SPC j l   Jumplist
+|    18 SPC j o   Back            C-o
 == snap help-group grid=100x40 cursor=7,22
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
 |  /tmp/pardes-snap/leader/cwd/cmds.txt                              Save New Del
@@ -357,16 +357,16 @@
 |     6 SPC c d   Delcol
 |     7 SPC c n   Newcol          topbar
 |     8 SPC d     Del
-|     9 SPC f f   Find            topbar
-|    10 SPC f g   Grep            topbar
-|    11 SPC f n   New             topbar
-|    12 SPC f s   Save
-|    13 SPC h t   Tutor           topbar
-|    14 SPC j i   Forward         C-i
-|    15 SPC j j   Last
-|    16 SPC j l   Jumplist
-|    17 SPC j o   Back            C-o
-|    18 SPC k     Kill            topbar
+|     9 SPC f c   Config
+|    10 SPC f f   Find            topbar
+|    11 SPC f g   Grep            topbar
+|    12 SPC f n   New             topbar
+|    13 SPC f s   Save
+|    14 SPC h t   Tutor           topbar
+|    15 SPC j i   Forward         C-i
+|    16 SPC j j   Last
+|    17 SPC j l   Jumplist
+|    18 SPC j o   Back            C-o
 == snap help-toggles grid=100x40 cursor=7,22
 |New Newcol Find Grep Help Tutor Dump NextColor Debug Kill
 |  /tmp/pardes-snap/leader/cwd/cmds.txt                              Save New Del