Add type hints to public APIs and configure mypy

- Improve mypy configuration with appropriate strictness settings
- Add comprehensive type hints to public API functions:
  - hookspecs.py: Type register_commands and prepare_connection hooks
  - plugins.py: Type get_plugins function and PluginManager
  - recipes.py: Type parsedate, parsedatetime, jsonsplit functions
  - utils.py: Type all public utility functions including rows_from_file,
    TypeTracker, ValueTracker, chunks, hash_record, flatten, etc.
  - db.py: Type Database, Queryable, Table, and View class methods
    including constructor, execute, query, table operations, etc.
- Exclude cli.py from strict checking (internal implementation detail)
- All public API modules now pass mypy type checking

Author: claude

mypy.ini

@@ -1,4 +1,32 @@
 [mypy]
+python_version = 3.10
+warn_return_any = False
+warn_unused_configs = True
+warn_redundant_casts = False
+warn_unused_ignores = False
+check_untyped_defs = True
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+no_implicit_optional = True
+strict_equality = True
 
-[mypy-pysqlite3,sqlean,sqlite_dump]
+[mypy-sqlite_utils.cli]
+ignore_errors = True
+
+[mypy-pysqlite3.*]
+ignore_missing_imports = True
+
+[mypy-sqlean.*]
+ignore_missing_imports = True
+
+[mypy-sqlite_dump.*]
+ignore_missing_imports = True
+
+[mypy-sqlite_fts4.*]
+ignore_missing_imports = True
+
+[mypy-pandas.*]
+ignore_missing_imports = True
+
+[mypy-numpy.*]
 ignore_missing_imports = True