Add comprehensive documentation for all project sections

Introduced new and updated documentation files across the docs/ directory, including project structure guides, function library references, and standardized READMEs for ct, install, vm, tools, api, and misc. This update fully documents all nine function libraries, provides quick start and learning paths, and mirrors the project structure for easier navigation and contribution.

docs/misc/install.func/INSTALL_FUNC_INTEGRATION.md

@@ -0,0 +1,104 @@
+# install.func Integration Guide
+
+How install.func integrates with the ProxmoxVED ecosystem and connects to other function libraries.
+
+## Component Integration
+
+### install.func in the Installation Pipeline
+
+```
+install/app-install.sh (container-side)
+    │
+    ├─ Sources: core.func (messaging)
+    ├─ Sources: error_handler.func (error handling)
+    │
+    ├─ ★ Uses: install.func ★
+    │  ├─ setting_up_container()
+    │  ├─ network_check()
+    │  ├─ update_os()
+    │  └─ motd_ssh()
+    │
+    ├─ Uses: tools.func (package installation)
+    │
+    └─ Back to install.func:
+       ├─ customize()
+       └─ cleanup_lxc()
+```
+
+### Integration with tools.func
+
+install.func and tools.func work together:
+
+```
+setting_up_container()          [install.func]
+    │
+update_os()                     [install.func]
+    │
+pkg_update()                    [tools.func]
+setup_nodejs()                  [tools.func]
+setup_mariadb()                 [tools.func]
+    │
+motd_ssh()                      [install.func]
+customize()                     [install.func]
+cleanup_lxc()                   [install.func]
+```
+
+---
+
+## Dependencies
+
+### External Dependencies
+
+- `curl`, `wget` - For downloads
+- `apt-get` or `apk` - Package management
+- `ping` - Network verification
+- `systemctl` or `rc-service` - Service management
+
+### Internal Dependencies
+
+```
+install.func uses:
+├─ core.func (for messaging and colors)
+├─ error_handler.func (for error handling)
+└─ tools.func (for package operations)
+```
+
+---
+
+## Best Practices
+
+### Always Follow This Pattern
+
+```bash
+#!/usr/bin/env bash
+source /dev/stdin <<<"$FUNCTIONS_FILE_PATH"
+
+# 1. Setup error handling
+catch_errors
+
+# 2. Initialize container
+setting_up_container
+
+# 3. Verify network
+network_check
+
+# 4. Update OS
+update_os
+
+# 5. Installation (your code)
+# ... install application ...
+
+# 6. Configure access
+motd_ssh
+
+# 7. Customize
+customize
+
+# 8. Cleanup
+cleanup_lxc
+```
+
+---
+
+**Last Updated**: December 2025
+**Maintainers**: community-scripts team