chore: add pedantic workspace lints (#90)

Add [workspace.lints.rust] and wire each member crate up with
[lints] workspace = true:

  unsafe_code = "deny"        (forbid would break the Android JNI build)
  single_use_lifetimes = "warn"
  trivial_casts = "warn"
  unused_lifetimes = "warn"
  unused_qualifications = "warn"
  variant_size_differences = "warn"
  unexpected_cfgs = "warn"

unsafe_code is "deny" rather than the issue's "forbid" so the three
Android JNI FFI modules (android_keystore, android_clipboard, safe_area)
can opt back in with a scoped #![allow(unsafe_code)] — forbid cannot be
locally overridden. Pure crates carry no unsafe and stay clean.

Clean up the warnings the new lints surface:
- 150ish unused_qualifications removed via `cargo fix` (purely syntactic
  redundant-path-prefix removals).
- table_plugin: the TABLE_COLOUR import was #[cfg(test)]-gated while the
  camera clear-colour used the fully-qualified path; unqualifying it left
  a non-test build with no import. Made the import unconditional instead.
- assets/sources: the `as &[u8]` casts in embed_*_svg! coerce each
  fixed-size &[u8; N] to a uniform slice so the tuples fit the
  &[(&str, &[u8])] arrays — load-bearing, so scoped #[allow(trivial_casts)].

Workspace clippy -D warnings and the full test suite pass. Android build
not compiled here (needs the NDK; built separately per CLAUDE.md §15) —
the deny + scoped-allow keeps the JNI unsafe blocks legal.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

solitaire_engine/src/ui_theme.rs

@@ -249,12 +249,12 @@ pub const BORDER_SUBTLE_HC: Color = Color::srgba(0.627, 0.627, 0.627, 1.0);
 pub struct HighContrastBorder {
     /// Border colour to use when high-contrast mode is *off* — the
     /// site's normal idle / active-state colour.
-    pub default_color: bevy::prelude::Color,
+    pub default_color: Color,
 }
 
 impl HighContrastBorder {
     /// Convenience constructor — `HighContrastBorder::with_default(BORDER_SUBTLE)`.
-    pub const fn with_default(default_color: bevy::prelude::Color) -> Self {
+    pub const fn with_default(default_color: Color) -> Self {
         Self { default_color }
     }
 }
@@ -282,18 +282,18 @@ impl HighContrastBorder {
 pub struct HighContrastBackground {
     /// Background colour to use when high-contrast mode is *off* —
     /// the site's normal idle / active-state colour.
-    pub default_color: bevy::prelude::Color,
+    pub default_color: Color,
     /// Background colour to use when high-contrast mode is *on*.
     /// Defaults to [`BORDER_SUBTLE_HC`] via [`with_default`].
     ///
     /// [`with_default`]: HighContrastBackground::with_default
-    pub hc_color: bevy::prelude::Color,
+    pub hc_color: Color,
 }
 
 impl HighContrastBackground {
     /// Convenience constructor — HC colour defaults to
     /// [`BORDER_SUBTLE_HC`].
-    pub const fn with_default(default_color: bevy::prelude::Color) -> Self {
+    pub const fn with_default(default_color: Color) -> Self {
         Self {
             default_color,
             hc_color: BORDER_SUBTLE_HC,
@@ -305,8 +305,8 @@ impl HighContrastBackground {
     /// marker which bumps `STATE_SUCCESS` → `STATE_SUCCESS_HC` rather
     /// than to a neutral gray.
     pub const fn with_hc(
-        default_color: bevy::prelude::Color,
-        hc_color: bevy::prelude::Color,
+        default_color: Color,
+        hc_color: Color,
     ) -> Self {
         Self {
             default_color,