fix(tests): sprint-37 sweep — #866, #869, #870 client test cleanup

#866: Fix _escape_bbcode in dialogue_box.gd — only escape '[', not ']'.
Chaining .replace(']', '[rb]') after .replace('[', '[lb]') corrupted the
[lb] escape itself. Updated test_dialogue_sprint18.gd accordingly.

#869: Migrate test_anti_tedium + test_bug_report_ring_buffer to instantiate
BugReportDialog via .tscn (BugReportDialogScene.instantiate()) instead of
bare Control.new() + set_script(). Sprint 36 moved bug_report_dialog.gd to
extends MetaScreen; the old load path was an orphan .uid file returning null.

#870: Delete 8 parse-error test files (test_debug_overlay_sprint19,
test_entanglement_sprint22, test_fog_sprint22, test_journal_sprint18,
test_minimap_sprint18, test_session_manager_sprint19, test_sprint30,
test_sprite_integration) + .uid sidecars. Coverage tickets filed for
fog/journal/minimap (#879, #880, #881). Sprint docs updated with #882 note.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/ui/dialogue_box.gd

@@ -625,8 +625,11 @@ func _format_entry(entry: Dictionary, alpha: float) -> String:
 
 
 ## Escape BBCode bracket characters in server-sourced text (Hoshe #2).
+## #866 fix: only escape '[' — unmatched ']' renders as a literal in RichTextLabel.
+## Chaining .replace("]", "[rb]") after .replace("[", "[lb]") corrupted the [lb] escape
+## itself: "[lb]" → "[lb[rb]", making the BBCode injection guard non-functional.
 static func _escape_bbcode(text: String) -> String:
-	return text.replace("[", "[lb]").replace("]", "[rb]")
+	return text.replace("[", "[lb]")
 
 
 ## Assign a palette color to an NPC entity ID on first encounter (#573).