Add analysis-dependent control logic and tooltips

Introduces logic to enable or disable UI controls based on whether video analysis is complete, with appropriate tooltips for disabled states. Updates all language files to include new tooltip strings. Ensures controls like subtitle selection, SponsorBlock, and merge subtitles are only enabled after analysis, improving user guidance and preventing invalid actions.

src/gui/ytsage_gui_video_info.py

@@ -300,11 +300,21 @@ class VideoInfoMixin:
 
             # Enable/disable the merge checkbox in the parent window
             if merge_checkbox:
-                # Only enable merge checkbox if we're not in Audio Only mode
+                # Only enable merge checkbox if we're not in Audio Only mode and analysis is complete
                 is_audio_only = hasattr(self, "audio_button") and self.audio_button.isChecked()
+                has_analysis = getattr(self, "analysis_completed", False)
                 # In audio-only mode, we still allow subtitle selection but not merging
-                should_enable = count > 0 and not is_audio_only
+                should_enable = count > 0 and not is_audio_only and has_analysis
                 merge_checkbox.setEnabled(should_enable)
+                # Update tooltip
+                if not has_analysis:
+                    merge_checkbox.setToolTip(_("main_ui.analyze_first_tooltip"))
+                elif is_audio_only:
+                    merge_checkbox.setToolTip(_("main_ui.audio_mode_disabled"))
+                elif count == 0:
+                    merge_checkbox.setToolTip(_("main_ui.select_subtitles_first"))
+                else:
+                    merge_checkbox.setToolTip("")
             else:
                 logger.warning("merge_subs_checkbox not found on parent window.")