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>

core/tdl_downloader.py

@@ -1,10 +1,10 @@
 """
-tdl_downloader.py — Fast file downloads via tdl (Go MTProto implementation).
+tdl_downloader.py - Fast file downloads via tdl (Go MTProto implementation).
 
 Install: https://github.com/iyear/tdl
     curl -sSL https://raw.githubusercontent.com/iyear/tdl/main/scripts/install.sh | bash
 
-First-time setup — log in once:
+First-time setup - log in once:
     tdl login               # saves to namespace "default"
     tdl login -n myns       # saves to a named namespace
 
@@ -77,7 +77,7 @@ def _build_cmd(urls: list[str], staging_dir: Path) -> list[str]:
     (no DialogID_MessageID_ prefix).
 
     --continue is kept so interrupted downloads resume rather than restart.
-    --skip-same is intentionally omitted — deduplication is handled upstream
+    --skip-same is intentionally omitted - deduplication is handled upstream
     by is_seen(), and --skip-same can cause the .tmp rename to fail when a
     same-named file already exists in the directory.
     """
@@ -103,7 +103,7 @@ def _build_cmd(urls: list[str], staging_dir: Path) -> list[str]:
 
 # ─── Runner ───────────────────────────────────────────────────────────────────
 
-# ANSI escape stripper — tdl emits colour codes even when not a TTY
+# ANSI escape stripper - tdl emits colour codes even when not a TTY
 import re as _re
 _ANSI_RE = _re.compile(r"\x1b\[[0-9;]*[mGKHFJA-Z]|\x1b=|\x1b>|\x1b\[\?[0-9]+[hl]")
 
@@ -141,7 +141,7 @@ async def _run_tdl(cmd: list[str], label: str) -> bool:
                     buf += chunk.decode(errors="replace")
                     # Split on both \r and \n; process all complete segments
                     parts = _re.split(r"[\r\n]", buf)
-                    # Last element may be an incomplete segment — keep in buffer
+                    # Last element may be an incomplete segment - keep in buffer
                     buf = parts[-1]
                     for part in parts[:-1]:
                         clean = _strip_ansi(part).strip()
@@ -163,7 +163,7 @@ async def _run_tdl(cmd: list[str], label: str) -> bool:
             log.info(f"[tdl] ✓ {label}")
             return True
         else:
-            log.error(f"[tdl] ✗ exit {proc.returncode} — {label}")
+            log.error(f"[tdl] ✗ exit {proc.returncode} - {label}")
             return False
     except FileNotFoundError:
         log.error("[tdl] binary not found at runtime")
@@ -260,7 +260,7 @@ async def download_batch_with_tdl(entries: list[BatchEntry]) -> dict[int, bool]:
         return {}
 
     if not is_tdl_available():
-        log.warning("[tdl] not available — all entries need Telethon fallback")
+        log.warning("[tdl] not available - all entries need Telethon fallback")
         return {e.doc_id: False for e in entries}
 
     urls: list[str] = []
@@ -327,7 +327,7 @@ async def download_single_with_tdl(msg, dest: Path) -> bool:
     bot_downloader where batching doesn't apply.
     """
     if not is_tdl_available():
-        log.warning("[tdl] not available — falling back to Telethon")
+        log.warning("[tdl] not available - falling back to Telethon")
         return False
 
     try: