Allow DMs to edit encounter name, description, and tactics

[Daren9m]

Problem

Generated name, description, and tactics are read-only, forcing DMs to export or recreate notes elsewhere.

Acceptance criteria

• The DM can edit encounter name, description, and tactics inline.
• Changes are reflected in print and JSON export.
• Changes persist when the encounter is saved and loaded.
• Editing narrative fields does not change monster composition, seed-derived stats, or difficulty.
• Controls are accessible and hidden or rendered cleanly in print.