style: replace !important with raised specificity for composer button

PR review CSS lint flagged the !important overrides. Obsidian's native
button defaults are beaten with a (0,3,1) selector chain
(.qoderian-input-wrapper .qoderian-input-toolbar button.qoderian-composer-action-btn)
instead, which also zeroes the native box-shadow. Verified on device:
brand-green fill and gray-black arrow unchanged, no native shadow.

Co-authored-by: QoderAI (Qwen 3.8 Max) <qoder_ai@qoder.com>

Author: luoxuanzao

src/style/components/input.css

@@ -356,14 +356,19 @@
   padding: 0;
   border: none;
   border-radius: 8px;
-  /* !important: Obsidian's native button defaults (interactive-normal gray)
-     out-specify a single class; sanctioned override per style/AGENTS.md */
-  background: var(--qoderian-brand) !important;
-  color: rgba(0, 0, 0, 0.7) !important;
   cursor: pointer;
   transition: filter 0.15s ease, opacity 0.15s ease;
 }
 
+/* Obsidian's native button defaults (interactive-normal gray) out-specify a
+   single class; raise specificity instead of !important to override them. */
+.qoderian-input-wrapper .qoderian-input-toolbar button.qoderian-composer-action-btn {
+  border: none;
+  box-shadow: none;
+  background: var(--qoderian-brand);
+  color: rgba(0, 0, 0, 0.7);
+}
+
 /* When the permission toggle is hidden the button inherits the row's
    right alignment instead of sitting next to the left group. */
 .qoderian-permission-toggle.qoderian-hidden ~ .qoderian-composer-action-btn {