feat: add CodeBuddy agent support

[studyzy]

Summary

Add full support for CodeBuddy as a supported coding agent, bringing the total from 11 to 12 auto-detected agents.

CodeBuddy follows the same configuration pattern as Claude Code, using ~/.codebuddy/ instead of ~/.claude/ and ~/.codebuddy/.mcp.json for MCP server registration.

Changes

Core (src/cli/)

• cli.h: Add bool codebuddy field to cbm_detected_agents_t; declare cbm_upsert_codebuddy_hooks, cbm_remove_codebuddy_hooks, cbm_upsert_codebuddy_session_hooks, cbm_remove_codebuddy_session_hooks
• cli.c: Add cbm_codebuddy_config_dir() (honors $CODEBUDDY_CONFIG_DIR, falls back to ~/.codebuddy), detection in cbm_detect_agents(), install_codebuddy_config(), uninstall_codebuddy(), PreToolUse + SessionStart hooks, hook gate script + session reminder script installers

Discovery (src/discover/)

• Add .codebuddy to skip directory list (IDE category)

CLI help (src/main.c)

• Add CodeBuddy to supported agents list

Setup scripts

• setup.sh: Add configure_codebuddy() — interactive MCP config for ~/.codebuddy/.mcp.json
• setup-windows.ps1: Add Configure-CodeBuddy — PowerShell equivalent, honors $env:CODEBUDDY_CONFIG_DIR

Tests

• Agent detection: cli_detect_agents_finds_codebuddy, cli_detect_agents_finds_codebuddy_via_env
• Hooks: cli_upsert_codebuddy_hook_fresh, cli_remove_codebuddy_hooks, cli_codebuddy_session_hook_parity
• Discovery: skip_codebuddy

Documentation

• README.md: Update badge 11→12, agent list, MCP table
• docs/index.html: Update meta tags and landing page copy

Test Plan

• make -f Makefile.cbm test — 5610 passed (was 5607, +3 new tests)
• make -f Makefile.cbm lint-format — clean
• make -f Makefile.cbm lint-no-suppress — clean
• bash -n scripts/setup.sh — syntax OK
• Production build (scripts/build.sh) — OK