chore(web): remove redundant and minimal README files

Removed 3 markdown files that provided no useful documentation:
- web/README.md: Single line "The frontend of Memos" (redundant)
- web/src/components/kit/README.md: Single line "Base components" (minimal)
- web/MARKDOWN_STYLE_GUIDE.md: Outdated styling guide (no longer applicable)

Kept comprehensive documentation files:
- web/src/components/MasonryView/README.md (implementation details)
- web/src/themes/COLOR_GUIDE.md (design system guide)
- web/src/components/ConfirmDialog/README.md (component API docs)
- web/src/store/README.md (architecture patterns)

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>

web/MARKDOWN_STYLE_GUIDE.md

-# Markdown Styling Guide
-
-This document describes the compact markdown styling approach used in this codebase.
-
-## Design Principles
-
-Our markdown rendering uses compact spacing optimized for memos and notes:
-
-### 1. **Scoped Styles**
-All markdown styles are scoped to `.markdown-content` to avoid global pollution:
-```css
-.markdown-content p { /* scoped */ }
-```
-
-### 2. **Compact Block Spacing**
-All block elements use **8px (0.5rem)** bottom margin:
-- Paragraphs
-- Lists (ul, ol)
-- Code blocks (pre)
-- Blockquotes
-- Tables
-- Horizontal rules
-
-This is more compact than GitHub's standard (16px) but maintains readability for memo-style content.
-
-### 3. **First/Last Child Normalization**
-```css
-.markdown-content > :first-child {
-  margin-top: 0 !important;
-}
-
-.markdown-content > :last-child {
-  margin-bottom: 0 !important;
-}
-```
-
-This prevents double margins at container boundaries.
-
-### 4. **Nested Element Spacing**
-Nested elements (lists within lists, paragraphs within lists) use **minimal spacing** (2px/0.125rem):
-```css
-.markdown-content li > ul {
-  margin-top: 0.125rem;
-  margin-bottom: 0.125rem;
-}
-```
-
-### 5. **Heading Separation**
-Headings have moderate top margins (12px/0.75rem) to create visual sections:
-```css
-.markdown-content h1,
-.markdown-content h2 {
-  margin-top: 0.75rem;
-  margin-bottom: 0.5rem;
-}
-```
-
-### 6. **No White-Space Preservation**
-We do NOT use `white-space: pre-line`. Spacing is controlled entirely by CSS margins, matching how GitHub/ChatGPT/Claude work.
-
-## Component Architecture
-
-We use a **hybrid approach**:
-
-### CSS-Based (for standard elements)
-```tsx
-<div className="markdown-content">
-  <ReactMarkdown>
-    {content}
-  </ReactMarkdown>
-</div>
-```
-
-Standard elements (p, ul, ol, h1-h6, etc.) are styled via CSS.
-
-### Component-Based (for custom elements)
-```tsx
-<ReactMarkdown
-  components={{
-    input: TaskListItem,   // Custom task list checkboxes
-    span: Tag,             // Custom #tag rendering
-  }}
->
-  {content}
-</ReactMarkdown>
-```
-
-Custom elements use React components for interactivity.
-
-## Comparison with Industry Standards
-
-| Feature | GitHub | ChatGPT | Claude | Memos (ours) |
-|---------|--------|---------|--------|--------------|
-| Block margin | 16px | 16px | 16px | 8px (compact) ⚡ |
-| Scoped styles | `.markdown-body` | `.prose` | Custom | `.markdown-content` ✅ |
-| First/last normalization | ✅ | ✅ | ✅ | ✅ |
-| Heading underlines (h1/h2) | ✅ | ❌ | ❌ | ✅ |
-| Custom components | Few | Many | Many | Some ✅ |
-| Line height | 1.6 | 1.6 | 1.6 | 1.5 (compact) ⚡ |
-| List padding | 2em | 2em | 2em | 1.5em (compact) ⚡ |
-| Code block padding | 16px | 16px | 16px | 8-12px (compact) ⚡ |
-
-**Note:** Our compact spacing is optimized for memo/note-taking apps where screen real estate is important.
-
-## Examples
-
-### Input
-```markdown
-1312
-
-* 123123
-```
-
-### Rendering
-- Paragraph "1312" with `margin-bottom: 0.5rem` (8px)
-- List with `margin-top: 0` (normalized)
-- Result: Single 8px gap between paragraph and list ✅
-
-### Before (with `white-space: pre-line`)
-```
-1312
-[blank line from preserved \n\n]
-[16px margin]
-* 123123
-```
-Result: Double spacing ❌
-
-### After (compact spacing, no white-space preservation)
-```
-1312
-[8px margin only]
-* 123123
-```
-Result: Clean, compact single spacing ✅
-
-## Testing
-
-To verify correct rendering:
-
-1. **Text followed by list**: `"text\n\n* item"` → single 8px gap
-2. **List followed by text**: `"* item\n\ntext"` → single 8px gap
-3. **Nested lists**: Should have minimal spacing (2px)
-4. **Headings**: Should have 12px top margin (except first child)
-5. **Blockquotes**: Should handle nested content properly
-6. **Code blocks**: Should have 8-12px padding (compact)
-7. **Tables**: Should have compact cell padding (4px vertical, 8px horizontal)
-
-## References
-
-- [CommonMark Spec](https://spec.commonmark.org/)
-- [GitHub Flavored Markdown Spec](https://github.github.com/gfm/)
-- [GitHub Markdown CSS](https://github.com/sindresorhus/github-markdown-css)
-- [Tailwind Typography](https://tailwindcss.com/docs/typography-plugin)

web/README.md

-# The frontend of Memos

web/src/components/kit/README.md

-# Base components in memos