Add debug console with teleport, stat editing, and spawn commands

[aebrer]

Summary

Add a developer/debug console toggled with the ~ key that lets us teleport the player, modify stats on the fly, and spawn items/entities anywhere. As the world gets more complex, this saves huge amounts of manual walking and RNG-wrangling when testing encounters, loot tables, and level transitions.

Current Behavior

There is no in-game debug tooling. Testing a specific level, enemy, item drop, or stat threshold requires playing through the game naturally or manually editing save/state files.

Proposed Behavior

A hidden LineEdit-based console overlay that opens with ~, accepts typed commands, supports Tab autocomplete, and closes with ~ or Escape. While open, game input (movement, camera, actions) is suppressed.

Acceptance Criteria

• ~ key toggles the console overlay visible/hidden
• Console has a scrollable output log and a single-line input field
• help command lists all available commands with brief usage
• Tab autocomplete cycles through matching commands and entity/item IDs
• teleport <x> <y> — instant move to grid coordinates in current level (player.snap_visual_position() + grid update)
• level <level_id> — transition to any loaded level (LevelManager.transition_to_level())
• stat <stat_name> <value> — set HP, Sanity, Max HP, Max Sanity, STR, PER, ANOM, etc. (StatBlock)
• spawn_item <item_id> [x] [y] — drop item at player position or specified grid coords (ItemSpawner.spawn_forced_item())
• spawn_entity <entity_id> [x] [y] — spawn entity at player position or specified grid coords (EntityRenderer.add_entity_billboard() / ChunkManager._spawn_debug_entity_near_player() pattern)
• clear or cls — empties the console output log
• Console blocks all gameplay input while focused
• Console works in both FPV and Tactical camera modes

Technical Notes

• UI: A CanvasLayer with a PanelContainer + RichTextLabel (output) + LineEdit (input), probably added to scenes/game.tscn or as a separate autoload scene.
• Input: Use _unhandled_input on the console to catch ~ when not focused; while focused, LineEdit handles text input. Consider adding a "debug_console" action to the InputMap.
• Command parser: Split by whitespace; first token is command, rest are args. Simple switch/lookup table.
• Autocomplete sources:
  • Commands: static array
  • Entity IDs: EntityRegistry._entities.keys() (or public getter)
  • Item IDs: may need to expose from ItemPool or item definition files
• Teleportation: Reuse player.snap_visual_position() after updating player.grid_position. Ensure chunk is loaded at target before teleporting.
• Entity/item spawn at arbitrary coords: Need to verify the target chunk is generated/loaded; if not, either force-load it or reject the command with a message.
• Dev-only gating: Could wrap initialization in a debug_enabled check, but since this is a single-player game with no anti-cheat concerns, always-available is fine as long as it's hidden.