v0.2 Phase 3: additive semantic tokens + KI-05 resolution

Additive token grammar (no renames, no replacements):

- --color-caution (dark #e8be4a, light #a08a1f) becomes the canonical
  name for tuned-amber notice surfaces in the new wrapper grammar
- --color-warning is kept as a CSS var() alias of --color-caution so
  every existing text-warning / bg-warning call site stays valid
- --color-info (dark #7a9ec0, light #3d6a8a) is the soft blue-grey
  signal for the new LumotiaNotice info variant
- --color-accent-environment (dark #8fae9a, light #4a7058) is an
  optional sage/moss support token for empty-state illustrations
  and environment-neutral status dots. NOT a brand swap — amber/
  copper --color-accent stays primary

Mirrored in src/design-system/colors_and_type.css (the buildless
preview pages bypass Tailwind so the duplication is intentional).

KI-05 resolved in the same commit, per the plan:

- src/lib/types/app.ts: drop `theme` from SettingsState
- src/lib/stores/page.svelte.ts: drop `theme: "Dark"` from defaults
- src/routes/+layout.svelte: drop the migration $effect, add a
  one-shot migrateLegacyTheme() on mount that copies any historical
  lumotia_settings.theme into preferences.theme and strips the
  legacy field. Idempotent — subsequent loads short-circuit
- src/routes/{float,viewer,preview}/+layout@.svelte: drop the same
  $effect; secondary windows inherit theme via PREFERENCES_CHANGED_EVENT
- src/lib/pages/SettingsPage.svelte: both SegmentedButton bindings
  (quick-settings row at :1272, Appearance group at :2606) now use
  Svelte 5 function bindings ({ get, set }) backed by prefs.theme
  and updatePreferences. No SegmentedButton API change

Phase 3 per-page gate green: npm run check (0/0/4129 files),
npm test (13/13), npm run test:e2e (16/16). No regressions in
the Phase 1 smoke baseline.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app.css

@@ -100,7 +100,18 @@
      (#1b1a17) verified mentally for each. */
   --color-success: #5fc28a;
   --color-danger: #e85f5f;
-  --color-warning: #e8be4a;
+  /* v0.2 coherence-pass aliases. `caution` is the canonical name in the
+     new wrapper grammar; `warning` is kept as a CSS var() alias so
+     existing `text-warning` / `bg-warning` call sites resolve to the
+     same value without a touch. */
+  --color-caution: #e8be4a;
+  --color-warning: var(--color-caution);
+  --color-info: #7a9ec0;
+
+  /* v0.2: optional support token for sage/moss surfaces — empty-state
+     illustrations, environmental neutral status dots. NOT a brand
+     swap; --color-accent (amber/copper) stays primary. */
+  --color-accent-environment: #8fae9a;
 
   /* Overlays — used by modal scrims. Derived from --color-bg #0f0e0c at
      0.7 alpha so the dim sits on the brand neutral, not pure black. */
@@ -190,7 +201,12 @@
      AA on cream backgrounds. */
   --color-success: #1f7344;
   --color-danger: #b32626;
-  --color-warning: #a08a1f;
+  /* v0.2 coherence-pass: --color-warning inherits @theme's
+     `var(--color-caution)`, so light theme only needs to redefine the
+     source token. */
+  --color-caution: #a08a1f;
+  --color-info: #3d6a8a;
+  --color-accent-environment: #4a7058;
 
   --color-sidebar: #f5f2ed;
   --color-nav-active: #eae6e0;