docs: Reorganize Usage section to highlight power features

Major restructuring of Usage section to put promptext's unique capabilities front and center:

Changes:
- Renamed "Basic Usage" → "Usage" and "Advanced Usage" merged in
- Lead with "Smart Context Building" showcasing -r and --max-tokens
- Show real-world examples: auth, database, API, bug investigation
- Consolidated quick commands into cleaner subsection
- Added "Token Budget Output" subsection for budget exceeded display
- Removed duplicate Output Formats subsection (kept main section)

The new flow immediately demonstrates what makes promptext powerful:
relevance filtering + token budgeting = smart AI context.

Users now see the killer features first, not buried in "Advanced" section.

Author: claude

README.md

@@ -82,84 +82,54 @@ promptext automatically checks for new releases once per day and notifies you wh
 - **Bug Investigation**: Let AI analyze related files together with proper context
 - **API Integration**: Generate structured code context for AI-powered development tools
 
-## Basic Usage
+## Usage
 
-```bash
-# Current directory to clipboard (PTX format)
-prx
-
-# Specific directory
-prx /path/to/project
-
-# Filter by extensions
-prx -e .go,.js,.ts
-
-# Summary only (file list, token counts)
-prx -i
+### Smart Context Building (The Power Features)
 
-# Output to file (format auto-detected from extension)
-prx -o context.ptx      # PTX format
-prx -o context.toon     # PTX format (backward compatibility)
-prx -o context.md       # Markdown
-prx -o project.xml      # XML
-
-# Explicit format specification
-prx -f ptx -o context.txt        # PTX: readable code blocks
-prx -f toon-strict -o small.txt  # TOON v1.3: maximum compression
-prx -f markdown -o context.md    # Standard Markdown
-prx -f xml -o project.xml        # XML structure
+```bash
+# Find authentication-related files within token budget
+prx -r "auth login OAuth session" --max-tokens 10000
 
-# Exclude patterns (comma-separated)
-prx -x "test/,vendor/" --verbose
+# Get database layer for Claude Haiku (8K limit)
+prx -r "database SQL postgres migration" --max-tokens 8000 -o db-context.ptx
 
-# Preview file selection without processing
-prx --dry-run -e .go
+# API routes for GPT-4 analysis
+prx -r "api routes handlers middleware" --max-tokens 15000
 
-# Suppress output (useful in scripts)
-prx -q -o output.ptx
+# Bug investigation: error handling code only
+prx -r "error exception handler logging" --max-tokens 5000 -e .go,.js
 ```
 
-## Advanced Usage
-
-### Relevance Filtering
+**How relevance scoring works:**
+- Filename match: 10 points
+- Directory path match: 5 points
+- Import statement match: 3 points
+- Content match: 1 point
 
-Rank files by keyword frequency:
+### Quick Commands
 
 ```bash
-# Authentication-related files
-prx --relevant "auth login OAuth session"
-
-# Database layer
-prx -r "database SQL postgres migration"
-
-# API endpoints
-prx -r "api routes handlers middleware"
-```
-
-**Scoring algorithm:**
-- Filename match: 10 points per occurrence
-- Directory path match: 5 points per occurrence
-- Import statement match: 3 points per occurrence
-- Content match: 1 point per occurrence
-
-Files ranked by total score. Ties broken by file size (smaller first).
-
-### Token Budget Control
+# Current directory to clipboard
+prx
 
-Enforce context window limits:
+# Specific directory with extension filter
+prx /path/to/project -e .go,.js,.ts
 
-```bash
-# Claude 3 Haiku limit
-prx --max-tokens 8000
+# Output to file (format auto-detected)
+prx -o context.ptx      # PTX (default)
+prx -o context.md       # Markdown
+prx -o project.xml      # XML
 
-# Combined relevance + budget
-prx -r "api routes handlers" --max-tokens 5000
+# Summary only (file list, token counts)
+prx -i
 
-# Cost optimization for iterative queries
-prx --max-tokens 3000 -o quick-context.ptx
+# Preview file selection
+prx --dry-run -r "auth"
 ```
 
-When budget exceeded, output shows inclusion/exclusion breakdown:
+### Token Budget Output
+
+When `--max-tokens` is set and exceeded, promptext shows exactly what was included and excluded:
 
 ```
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