feat: add Open WebUI PostgreSQL code export script

Added artifact_postgres_export.sh to automate exporting code artifacts
from Open WebUI chat conversations stored in PostgreSQL.

Features:
- Direct PostgreSQL database access via Docker exec
- Remote server support via SSH (--remote flag)
- Automatic filename detection from markdown headers
- Directory structure preservation (src/main.rs, src/parser/mod.rs, etc.)
- Safety checks: UUID validation, empty directory check (--force override)
- Colored terminal output with verbose mode
- Smart code block extraction with language detection
- Support for 20+ file extensions (Rust, Python, JS, YAML, etc.)
- No metadata file pollution in output directory

Usage:
  artifact_postgres_export.sh [OPTIONS] <chat_id> <output_dir>

Example:
  artifact_postgres_export.sh --remote vps e135d74e-5b43-4b24-a651-e999f103942b ~/Projects/rust/piglet

Updated README.md with comprehensive documentation including:
- Full option reference
- Usage examples
- Feature list

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

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

README.md

@@ -6,6 +6,7 @@ This documentation was auto-generated using [`doc_bash_generate.sh`](https://git
 
 ## Table of Contents
 - [`artifact_github_download.sh`](#artifact-github-download-sh)
+- [`artifact_postgres_export.sh`](#artifact-postgres-export-sh)
 - [`css_color_filter.sh`](#css-color-filter-sh)
 - [`css_color_palette.sh`](#css-color-palette-sh)
 - [`css_json_convert.sh`](#css-json-convert-sh)
@@ -84,6 +85,79 @@ artifact_github_download.sh valknarness/awesome -n awesome-database-latest -o ~/
 
 ---
 
+## `artifact_postgres_export.sh`
+
+Export code artifacts from Open WebUI PostgreSQL database
+
+### Usage
+
+```bash
+artifact_postgres_export.sh [OPTIONS] <chat_id> <output_dir>
+```
+
+### Arguments
+
+- `chat_id` - Chat ID from Open WebUI URL (UUID format)
+- `output_dir` - Directory to save extracted code files (optional, defaults to current directory)
+
+### Options
+
+<details>
+<summary>Click to expand full help output</summary>
+
+```
+artifact_postgres_export.sh - Export code artifacts from Open WebUI PostgreSQL database
+
+Usage: artifact_postgres_export.sh [OPTIONS] <chat_id> <output_dir>
+
+Arguments:
+  chat_id      Chat ID from Open WebUI URL (e.g., e135d74e-5b43-4b24-a651-e999f103942b)
+  output_dir   Directory to save extracted code files
+
+Options:
+  -h, --help           Show this help message
+  -H, --host HOST      PostgreSQL host (default: ai_postgres via Docker)
+  -u, --user USER      PostgreSQL user (default: ai)
+  -d, --db DATABASE    PostgreSQL database (default: openwebui)
+  -v, --verbose        Verbose output
+  --remote HOST        SSH remote host for Docker access (default: vps)
+  -f, --force          Force export even if output directory is not empty
+
+Examples:
+  artifact_postgres_export.sh e135d74e-5b43-4b24-a651-e999f103942b ~/Projects/rust/piglet
+  artifact_postgres_export.sh --remote vps abc123def456 ./output
+```
+
+</details>
+
+### Examples
+
+```bash
+# Export chat to local directory
+artifact_postgres_export.sh e135d74e-5b43-4b24-a651-e999f103942b ~/Projects/rust/piglet
+
+# Export from remote server
+artifact_postgres_export.sh --remote vps abc123def456 ./output
+
+# Force export to non-empty directory
+artifact_postgres_export.sh -f e135d74e-5b43-4b24-a651-e999f103942b ./output
+
+# Verbose output with custom database
+artifact_postgres_export.sh -v -d custom_db abc123def456 ./output
+```
+
+### Features
+
+- **Direct PostgreSQL access** via Docker exec (SSH-enabled for remote servers)
+- **Automatic filename detection** from markdown headers (e.g., `### src/main.rs`)
+- **Directory structure preservation** - maintains original paths like `src/parser/duration.rs`
+- **Safety checks** - validates chat ID format and checks for empty output directory
+- **Colored output** - uses ANSI colors for better readability
+- **Smart code extraction** - parses markdown code blocks with language detection
+- **File extension mapping** - supports 20+ file types (Rust, Python, JavaScript, etc.)
+
+---
+
 ## `css_color_filter.sh`
 
 CSS Color Filter Generator