feat: output path defaults (#43) + datetime precision & dedup (#47)

#43 — Имя файла и пути по умолчанию:
- resolve_output_path() в yaml_config.py: резолвит --output с учётом
  output.dir, filename_template, default_format из YAML-конфига
- Bare format (xlsx/odt/...) → путь по шаблону
- Без расширения → автодописывается default_format (.xlsx)
- Config.get_output_dir/filename/default_format()

#47 — datetime precision и дедупликация:
- period.last_used.from/to в YAML-конфиге и AppConfig
- period.precision: date|datetime
- _compute_dedup_cutoff() в cli.py: при precision=datetime вычисляет
  cutoff из period.last_used.to
- _parse_datetime() + AND-логика дедупликации в client.py:
  запись исключается если created_on И updated_on < cutoff
- Пропуск issues без часов после дедупликации

Closes #43
Closes #47

redmine_reporter/yaml_config.py

@@ -99,3 +99,53 @@ def expand_filename_template(
     for key, value in replacements.items():
         result = result.replace("{" + key + "}", value)
     return result
+
+
+KNOWN_FORMAT_NAMES = {"xlsx", "odt", "csv", "md", "html", "json"}
+
+
+def resolve_output_path(
+    output_arg: str | None,
+    *,
+    output_dir: str = "",
+    filename_template: str = "{author}_{from}_{to}.{ext}",
+    default_format: str = "xlsx",
+    author: str = "",
+    from_date: str = "",
+    to_date: str = "",
+) -> str | None:
+    """Resolve the final output path from --output argument and config settings.
+
+    Returns None if output_arg is None (meaning no file output, use console).
+
+    Resolution rules:
+      - None → None (console output)
+      - Bare format name (xlsx, odt, csv, md, html, json) → use template path
+      - Path without extension → append .{default_format}
+      - Path with known extension → use as-is
+      - Path with unknown extension → use as-is
+    """
+    if output_arg is None:
+        return None
+
+    arg = output_arg.strip()
+
+    import os
+
+    if arg.lower() in KNOWN_FORMAT_NAMES:
+        ext = arg.lower()
+        resolved_dir = os.path.expanduser(output_dir) if output_dir else "."
+        filename = expand_filename_template(
+            filename_template,
+            author=author,
+            from_date=from_date,
+            to_date=to_date,
+            ext=ext,
+        )
+        return os.path.join(resolved_dir, filename)
+
+    _, ext = os.path.splitext(arg)
+    if not ext:
+        arg = f"{arg}.{default_format}"
+
+    return arg