Fix script text area mouse clicks on 26.3

[rubensworks]

Related to CyclopsMC/IntegratedDynamics#1750 (same root cause as CyclopsMC/IntegratedTerminals#230).

Cause

Minecraft 26.3 moved input to SDL, so MouseButtonEvent.button() now uses left 1, middle 2, right 3 (InputConstants.MOUSE_BUTTON_*). Before, it used GLFW's left 0, right 1, middle 2. WidgetTextArea still used the old values:

• mouseClicked: the "right click selects all" check (== 1) now matches a left click, so every left click selected the whole script instead of placing the cursor.
• mouseClicked and mouseDragged: the left-click cursor placement and drag selection (== 0) never ran.

Fix

Compare against InputConstants.MOUSE_BUTTON_RIGHT and MOUSE_BUTTON_LEFT.

Validation

• ./gradlew build passes, and ./gradlew runGameTestServer passes all 23 required tests.
• Checked in a NeoForge 26.3 dev client: a Scripting Terminal with a drive and disk, editing a script containing hello world.
  • This branch: a left click placed the cursor at position 6, a drag selected hell, and a right click selected everything.
  • Original master-26 widget, hotswapped into the same client: the left click and the drag both just selected all of hello world.

🤖 Generated with Claude Code

https://claude.ai/code/session_016VFfUPDxbJ8RqPeQHsAbh7

[coveralls]

Coverage Report for CI Build 36165311246

Coverage at 51.638% (no base build to compare)

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	2618
Covered Lines:	1481
Line Coverage:	56.57%
Relevant Branches:	862
Covered Branches:	316
Branch Coverage:	36.66%
Branches in Coverage %:	Yes
Coverage Strength:	20.5 hits per line

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💛 - Coveralls