[arenabuddy] Update CLI documentation and fix MTGA database file extension (#323)

This pull request updates the CLI documentation and fixes a critical bug in the MTGA database detection logic.

**Documentation Updates:**
- Clarified that the CLI tool is named `arenabuddyctl`
- Added comprehensive examples showing how to run commands using `cargo run -p arenabuddy_cli`
- Documented the new `scrape-mtga` command with auto-detection of MTGA install paths and custom path options
- Added examples for the REPL and event-log commands
- Updated help command examples to use the correct cargo syntax

**Bug Fix:**
- Fixed incorrect file extension filter in MTGA database detection - changed from `.rs` to `.mtga` to properly locate `Raw_CardDatabase_*.mtga` files

Author: gazure

arenabuddy/README.md

@@ -19,17 +19,30 @@ To get started with the ArenaBuddy development environment, follow these steps:
 
 3. CLI Tool:
 
-   The consolidated CLI tool provides functionality for log parsing, card scraping:
+   The consolidated CLI tool (`arenabuddyctl`) provides functionality for log parsing, card scraping, and more:
 
    ```bash
-   # Scrape card data from online sources
-   arenabuddy scrape
+   # Scrape card data from local MTGA database + Scryfall enrichment
+   # (auto-detects MTGA install path on macOS/Windows/Linux)
+   cargo run -p arenabuddy_cli -- scrape-mtga --output ./cards.pb
+
+   # Optionally specify a custom MTGA install path
+   cargo run -p arenabuddy_cli -- scrape-mtga --mtga-path /path/to/MTGA/.../Raw --output ./cards.pb
+
+   # Scrape card data from online sources (17Lands + Scryfall)
+   cargo run -p arenabuddy_cli -- scrape --output ./cards.pb
 
    # Parse MTGA log files
-   arenabuddy parse --player-log /path/to/Player.log
+   cargo run -p arenabuddy_cli -- parse --player-log /path/to/Player.log
+
+   # Start interactive REPL for card searches
+   cargo run -p arenabuddy_cli -- repl --cards-db ./cards.pb
+
+   # Generate structured event log from a Player.log
+   cargo run -p arenabuddy_cli -- event-log --player-log /path/to/Player.log
    ```
 
-   You can get help on any command with `arenabuddy --help` or `arenabuddy <command> --help`.
+   You can get help on any command with `cargo run -p arenabuddy_cli -- --help` or `cargo run -p arenabuddy_cli -- <command> --help`.
 
 4. Project Structure:
 

arenabuddy/cli/src/commands/scrape_mtga.rs

@@ -108,7 +108,7 @@ fn find_mtga_database(mtga_path: Option<&PathBuf>) -> Result<PathBuf> {
         let path = entry.path();
         if let Some(name) = path.file_name().and_then(|n| n.to_str())
             && name.starts_with("Raw_CardDatabase_")
-            && path.extension().is_some_and(|ext| ext.eq_ignore_ascii_case("rs"))
+            && path.extension().is_some_and(|ext| ext.eq_ignore_ascii_case("mtga"))
         {
             return Ok(path);
         }