fix: improve tag spacing with flexbox layout

Fixes #577

## Problem
Tag spacing breaks when using fonts other than the default. The negative margins (-me-3.5, -me-5) are hardcoded for the default monospace font.

## Solution
Replace negative margin approach with flexbox layout, matching the pattern used by other icon+text components in AstroPaper (Datetime, EditPost, BackButton).

## Changes
- li: Removed 'inline-block' (not needed)
- a: Changed to 'flex items-center gap-x-1.5' (matches Datetime pattern)
- IconHash: Removed negative margins, use gap for spacing
- Removed   entity (gap handles spacing)

## Benefits
- Works with any font (not calibrated to specific font)
- Follows existing AstroPaper component patterns
- Standard Tailwind CSS (no magic numbers)
- Self-adjusting spacing

Author: clouatre

src/components/Tag.astro

@@ -20,17 +20,17 @@ const { tag, tagName, size = "sm" } = Astro.props;
     href={`/tags/${tag}/`}
     transition:name={tag}
     class:list={[
-      "relative pe-2 text-lg underline decoration-dashed group-hover:-top-0.5 group-hover:text-accent focus-visible:p-1 focus-visible:no-underline",
+      "flex items-center gap-x-1.5 text-lg underline decoration-dashed group-hover:-top-0.5 group-hover:text-accent focus-visible:p-1 focus-visible:no-underline",
       { "text-sm": size === "sm" },
     ]}
   >
     <IconHash
       class:list={[
-        "inline-block opacity-80",
-        { "-me-3.5 size-4": size === "sm" },
-        { "-me-5 size-6": size === "lg" },
+        "opacity-80",
+        { "size-4": size === "sm" },
+        { "size-6": size === "lg" },
       ]}
     />
-    &nbsp;<span>{tagName}</span>
+    <span>{tagName}</span>
   </a>
 </li>