Redesign the native lock screen: clock/avatar header, on-screen keyboard, wrong-password shake

The native lock UI was a flat bordered rectangle with three left-aligned
text lines and no shadow, clock, or identity marker - reported directly
as looking unfinished. Splits the redesign across a new transparent-canvas
header (time, date, circular avatar, username) above a redesigned,
centered password box with a real drop shadow and a dimmed placeholder
prompt, plus a genuine on-screen QWERTY-shaped keyboard with working
Shift/Backspace/Return/Space and real click hit-testing shared with the
render path via one `lock_stack_layout` function, and a damped-sine shake
on a failed attempt.

LockConfig gains show_clock/show_keyboard/avatar_bg, each independently
srd.set-able and documented in a new theme.lock.* section in DEFAULTS.md.
native_lock_render_elements now takes one NativeLockFrame struct instead
of positional buffer arguments now that it composites five optional
layers instead of two.

Full workspace build/test/clippy clean (152 wayland tests, +6 new).

1 files changed, 3 insertions, 3 deletions

diff --git a/crates/wayland/src/decoration.rs b/crates/wayland/src/decoration.rs
index ee3f34c..aa12a54 100644
--- a/crates/wayland/src/decoration.rs
+++ b/crates/wayland/src/decoration.rs
@@ -44,7 +44,7 @@ pub(crate) use color::{mix_rgb, rgb_to_bgra};
 pub(crate) use corners::{round_bottom_corners, round_top_corners};
 pub(crate) use font::{blit_glyph, find_system_font, FONT_PIXELS, TEXT_LEFT_PADDING};
 pub use shadow::{shadow_bitmap, shadow_rect};
-pub(crate) use shadow::SHADOW_MAX_ALPHA;
+pub(crate) use shadow::{SHADOW_MAX_ALPHA, SHADOW_SIZE};
 pub use titlebar::render_titlebar;
 
 /// Default corner radius, in pixels, applied to a window at creation
@@ -389,7 +389,7 @@ pub(crate) fn render_desktop_icon(
 /// canvas), so there's no premultiplication to get right here - straight
 /// and premultiplied colour are identical at full opacity.
 #[allow(clippy::too_many_arguments)]
-fn fill_rect(buf: &mut [u8], width: usize, height: usize, x0: i32, y0: i32, x1: i32, y1: i32, color: (u8, u8, u8), alpha: u8) {
+pub(crate) fn fill_rect(buf: &mut [u8], width: usize, height: usize, x0: i32, y0: i32, x1: i32, y1: i32, color: (u8, u8, u8), alpha: u8) {
     let px = rgb_to_bgra(color, alpha);
     for y in y0.max(0)..y1.min(height as i32) {
         for x in x0.max(0)..x1.min(width as i32) {
@@ -410,7 +410,7 @@ fn fill_rect(buf: &mut [u8], width: usize, height: usize, x0: i32, y0: i32, x1:
 /// partial-alpha pixel is a real, previously-hit correctness bug here, not
 /// a style choice.
 #[allow(clippy::too_many_arguments)]
-fn blit_glyph_on_transparent(buf: &mut [u8], width: usize, height: usize, glyph_x: i32, glyph_y: i32, metrics: &fontdue::Metrics, coverage: &[u8], color: (u8, u8, u8)) {
+pub(crate) fn blit_glyph_on_transparent(buf: &mut [u8], width: usize, height: usize, glyph_x: i32, glyph_y: i32, metrics: &fontdue::Metrics, coverage: &[u8], color: (u8, u8, u8)) {
     for row in 0..metrics.height {
         let y = glyph_y + row as i32;
         if y < 0 || y as usize >= height {