♻️ Restore .cursor/rules as canonical architecture (#12)

Reverts the v2 "cross-tool architecture" that made rules/ canonical.
Returns to standard Cursor architecture where .cursor/rules is the
canonical location.

## Changes

**Directory Structure (THIS REPO):**
- Moved rules/ → .cursor/rules/ (canonical location)
- Created rules/ symlink → .cursor/rules/ (visibility only)

**User Projects:**
- .cursor/rules/ is canonical (no root-level symlink)
- Simplified bootstrap to create .cursor/rules directly
- Legacy v2 detection suggests migration

**Documentation:**
- Updated /ai-coding-config command with correct architecture
- Removed Windsurf support (deprecated after Google acquisition)
- Updated AGENTS.md, bootstrap script, and README

**Rationale:**
The v2 "cross-tool" architecture with rules/ at root was a mistake.
Cursor rules belong in .cursor/rules/. This repo has rules/ symlink
for visibility, but user projects should use .cursor/rules/ directly.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Nick Sullivan <nick@technick.ai>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: 3 people

.cursor/rules

@@ -59,20 +59,18 @@ ln -s $AI_CONFIG/.cursor .cursor
 
 ```bash
 # From your project directory
-mkdir -p rules
-ln -s ../rules .cursor/rules  # Symlink for Cursor compatibility
-ln -s $AI_CONFIG/rules/python rules/python
-ln -s $AI_CONFIG/rules/django rules/django
+mkdir -p .cursor/rules
+ln -s $AI_CONFIG/.cursor/rules/python .cursor/rules/python
+ln -s $AI_CONFIG/.cursor/rules/django .cursor/rules/django
 ```
 
 ### Pattern 3: Copy What You Need
 
 ```bash
 # From your project directory
-mkdir -p rules
-ln -s ../rules .cursor/rules  # Symlink for Cursor compatibility
-cp $AI_CONFIG/rules/*.mdc rules/
-cp -r $AI_CONFIG/rules/python rules/
+mkdir -p .cursor/rules
+cp $AI_CONFIG/.cursor/rules/*.mdc .cursor/rules/
+cp -r $AI_CONFIG/.cursor/rules/python .cursor/rules/
 ```
 
 ## Manual Invocation