Rename to stealergram, add pyproject.toml, purge em-dashes

- Rename project to stealergram throughout
- Add pyproject.toml (replaces requirements.txt split, folds pytest.ini)
- Replace all em-dashes with hyphens across all source files

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

main.py

@@ -1,5 +1,5 @@
 """
-main.py — Entry point for the ULP credential monitor.
+main.py - Entry point for the ULP credential monitor.
 
 Usage:
     python main.py               # TUI mode (default)
@@ -55,7 +55,7 @@ def _start_web_thread(host: str, port: int) -> threading.Thread:
 # ─── Plain CLI mode ───────────────────────────────────────────────────────────
 
 async def _cli_main():
-    """Original asyncio main — runs without the TUI."""
+    """Original asyncio main - runs without the TUI."""
     logging.getLogger().addHandler(logging.StreamHandler(sys.stdout))
 
     from telethon import TelegramClient
@@ -64,7 +64,7 @@ async def _cli_main():
     from core.scraper import backfill_all, register_handlers, warm_entity_cache
 
     log.info("=" * 60)
-    log.info("  ULP Credential Monitor — CLI mode")
+    log.info("  ULP Credential Monitor - CLI mode")
     log.info("=" * 60)
 
     patterns = compile_patterns(config.TARGET_KEYWORDS)