Migrate to per-agent subdirectories, uniform 8-agent support, cross-platform fixes

- All paths use ~/.elydora/{agentId}/ per-agent isolation
- Add copilot, letta plugins; split kiro into kirocli + kiroide
- Remove augment (SDK-only agent, not one-click)
- Fix guard command: use sys.executable instead of hardcoded python3
- Fix chmod wrapped in try/except for Windows compatibility
- Fix OpenCode chain state: save after HTTP 2xx response
- Fix guard script shebang consistency (sys.executable)
- Uniform 8 agents: claudecode, cursor, gemini, kirocli, kiroide, opencode, copilot, letta

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

elydora/plugins/registry.py

@@ -11,6 +11,11 @@ SUPPORTED_AGENTS: Dict[str, Dict[str, str]] = {
         "hook_event": "PostToolUse",
         "config_path": "~/.claude/settings.json",
     },
+    "copilot": {
+        "name": "Copilot CLI",
+        "hook_event": "PostToolUse",
+        "config_path": ".github/hooks/hooks.json",
+    },
     "cursor": {
         "name": "Cursor",
         "hook_event": "PostToolUse",
@@ -21,16 +26,21 @@ SUPPORTED_AGENTS: Dict[str, Dict[str, str]] = {
         "hook_event": "AfterTool",
         "config_path": "~/.gemini/settings.json",
     },
-    "augment": {
-        "name": "Augment Code",
+    "kirocli": {
+        "name": "Kiro CLI",
         "hook_event": "PostToolUse",
-        "config_path": "~/.augment/settings.json",
+        "config_path": "~/.kiro/settings.json",
     },
-    "kiro": {
-        "name": "Kiro",
+    "kiroide": {
+        "name": "Kiro IDE",
         "hook_event": "PostToolUse",
         "config_path": "~/.kiro/hooks/",
     },
+    "letta": {
+        "name": "Letta Code",
+        "hook_event": "PostToolUse",
+        "config_path": "~/.letta/settings.json",
+    },
     "opencode": {
         "name": "OpenCode",
         "hook_event": "PostToolUse",