fix: DM reactions + eradicate broken CSS variable opacity modifiers

Server-side: handleReactionAdd/Remove now check dm_messages table when
message isn't found in server messages, enabling DM emoji reactions
via the same unified client event path.

Client-side: replaced all remaining broken opacity modifiers on CSS
variables (border-border-soft/50, bg-accent-rose/10, bg-surface-*/N,
etc.) with explicit rgba values. Tailwind can't decompose var() for
opacity, causing fallback to currentColor. Fixes 16 files across
error boxes, table borders, surface tints, and input separators.

packages/web/src/components/chat/FriendsPage.tsx

@@ -161,7 +161,7 @@ export function FriendsPage() {
               </button>
             </form>
             {addStatus && (
-              <div className={`text-sm p-3 rounded-lg border ${addStatus.type === 'success' ? 'text-txt-positive border-status-online/20 bg-status-online/5' : 'text-txt-danger border-accent-rose/20 bg-accent-rose/5'}`}>
+              <div className={`text-sm p-3 rounded-lg border ${addStatus.type === 'success' ? 'text-txt-positive border-[rgba(134,239,172,0.20)] bg-[rgba(134,239,172,0.05)]' : 'text-txt-danger border-[rgba(253,164,175,0.20)] bg-[rgba(253,164,175,0.05)]'}`}>
                 {addStatus.message}
               </div>
             )}