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>

tui/app.md

@@ -34,8 +34,8 @@ MonitorApp (App)
 
 ### Threading model
 - **Bot backend** → `threading.Thread(daemon=True)` with its own `asyncio.new_event_loop()`  
-  Runs `_bot_main()` — Telethon is completely isolated from Textual's loop.
-- **TUI drain** → `set_interval(0.1, _drain_bus)` — polls `queue.Queue` every 100ms on Textual's loop.
+  Runs `_bot_main()` - Telethon is completely isolated from Textual's loop.
+- **TUI drain** → `set_interval(0.1, _drain_bus)` - polls `queue.Queue` every 100ms on Textual's loop.
 
 ### Key methods
 
@@ -105,7 +105,7 @@ Changes apply immediately (handler re-registered). Not persisted to `config.py`
 - Validates regex before adding
 - On change: rebuilds `utils.scorer.EMPLOYEE_DOMAINS` and `ORG_DOMAINS`
 - Bot handler recompiles patterns on the next incoming message automatically
-- **Changes are in-memory only** — copy to `config.py` to persist
+- **Changes are in-memory only** - copy to `config.py` to persist
 
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