feat(theme): bump accent chroma, push sensory zones apart, richer status tokens

Phase 10b colour push: theme reads as Magnotia, not "subdued generic dark".
Same lightness band as Phase 10a (AA preserved), more chroma across accent,
status tokens, and zone surfaces.

Dark accent: #c98555 -> #d68450 (subtle/hover/glow recomputed).
Light accent: #a06a3e -> #a3683a.
Dark status: success #7ec89a -> #5fc28a, danger #e87171 -> #e85f5f,
warning #e8c86e -> #e8be4a.
Light status: success #2f7549 -> #1f7344, danger #a83838 -> #b32626,
warning #b89a3e -> #a08a1f.

Sensory zones pushed further apart so each zone reads as its own
environment: cave cools toward blue-grey, energy warms toward red-orange,
reset cools toward green. AA on body text verified for every Card surface
in both themes.

Stale accent rgba (201,133,85) replaced with new (214,132,80) across nine
files. --shadow-accent in colors_and_type.css mirrored.

No secondary tint token added: Magnotia's identity is amber-as-the-only-
meaningful-colour. Cheaper to add a second meaningful colour later if a
real need appears than to dilute the discipline now.

Default surfaces, text tokens, and borders untouched per scope.

src/lib/pages/FilesPage.svelte

@@ -187,7 +187,7 @@
   <div class="flex items-center gap-2 px-7 pb-3">
     <button
       class="btn-lg rounded-lg font-medium text-white bg-accent hover:bg-accent-hover
-             shadow-[0_2px_8px_rgba(201,133,85,0.2)]"
+             shadow-[0_2px_8px_rgba(214,132,80,0.2)]"
       onclick={handleBrowse}
       disabled={transcribing}
     >
@@ -213,7 +213,7 @@
     <div class="px-7 pb-3 animate-fade-in">
       <div class="h-[3px] bg-bg-elevated rounded-full overflow-hidden">
         <div
-          class="h-full bg-accent rounded-full shadow-[0_0_8px_rgba(201,133,85,0.4)]"
+          class="h-full bg-accent rounded-full shadow-[0_0_8px_rgba(214,132,80,0.4)]"
           style="width: {progress}%; transition-duration: var(--duration-ui)"
         ></div>
       </div>