feat: add plugin support to shared directories (v4.3.6) (#15)

* feat(shared): add plugin support to shared directories

Add Claude Code plugins to the .ccs/shared/ symlink architecture,
enabling plugin sharing across all CCS profiles (GLM, GLMT, Kimi, etc).

Changes:
- SharedManager: Add 'plugins' to sharedDirs array
- Help text: Update all three implementations (Node.js, bash, PowerShell)
- Postinstall: Create ~/.ccs/shared/plugins/ directory on install

Architecture:
~/.claude/plugins/ <- ~/.ccs/shared/plugins/ <- instance/plugins/

This follows the existing pattern for commands/skills/agents and
maintains cross-platform compatibility with Windows fallback support.

* chore: bump version to 4.3.6

* docs: update CHANGELOG for v4.3.6

lib/ccs

@@ -2,7 +2,7 @@
 set -euo pipefail
 
 # Version (updated by scripts/bump-version.sh)
-CCS_VERSION="4.3.5"
+CCS_VERSION="4.3.6"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 readonly CONFIG_FILE="${CCS_CONFIG:-$HOME/.ccs/config.json}"
 readonly PROFILES_JSON="$HOME/.ccs/profiles.json"
@@ -222,7 +222,8 @@ show_help() {
   echo -e "  Commands:    ~/.ccs/shared/commands/"
   echo -e "  Skills:      ~/.ccs/shared/skills/"
   echo -e "  Agents:      ~/.ccs/shared/agents/"
-  echo -e "  Note: Commands, skills, and agents are symlinked across all profiles"
+  echo -e "  Plugins:     ~/.ccs/shared/plugins/"
+  echo -e "  Note: Commands, skills, agents, and plugins are symlinked across all profiles"
   echo ""
 
   echo -e "${CYAN}Examples:${RESET}"

lib/ccs.ps1

@@ -12,7 +12,7 @@ param(
 $ErrorActionPreference = "Stop"
 
 # Version (updated by scripts/bump-version.sh)
-$CcsVersion = "4.3.5"
+$CcsVersion = "4.3.6"
 $ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
 $ConfigFile = if ($env:CCS_CONFIG) { $env:CCS_CONFIG } else { "$env:USERPROFILE\.ccs\config.json" }
 $ProfilesJson = "$env:USERPROFILE\.ccs\profiles.json"
@@ -269,7 +269,8 @@ function Show-Help {
     Write-Host "  Commands:    ~/.ccs/shared/commands/"
     Write-Host "  Skills:      ~/.ccs/shared/skills/"
     Write-Host "  Agents:      ~/.ccs/shared/agents/"
-    Write-Host "  Note: Commands, skills, and agents are symlinked across all profiles"
+    Write-Host "  Plugins:     ~/.ccs/shared/plugins/"
+    Write-Host "  Note: Commands, skills, agents, and plugins are symlinked across all profiles"
     Write-Host ""
 
     Write-ColorLine "Examples:" "Cyan"