Show syntax errors in the scripting terminal editor

[rubensworks]

Phase 4 of the scripting terminal UX improvements, stacked on #79 (then #78, then #77).

Problem

A syntax error in a script only became visible once a variable card using it was evaluated, e.g. as an X in a display panel that you then had to hover (see #5). The terminal itself gave no feedback, and the info book said so too.

Changes

Show syntax errors in the script editor

• ILanguageHandler gets a default checkSyntax(Path, String) that returns null, so other language handlers keep working.
• The JavaScript handler implements it with GraalJS Context.parse, which parses the script without executing it.
• The server checks the active script once it has been unchanged for 10 ticks, and only re-checks when the content changes. The result goes to the client in a new TerminalScriptingSyntaxErrorPacket.
• The editor underlines the error position, and hovering the line shows the message.
• The info book text that said the editor can't detect syntax errors is updated (en_us only).

Make the syntax error marker easier to see

• With only the line number turned red, at half size, the error line was easy to miss, and nothing showed an error that was scrolled out of view.
• The gutter cell of the error line now gets a light red background, and the scrollbar shows a red tick at the error's position.

Validation

In a dev client (clientdevbridge), with a missing ) on line 7 of a 40-line script:

• Before: nothing in the editor indicates a problem.
• After: line 7's gutter is red, the ; is underlined, and hovering shows SyntaxError: script0.js:7:23 Expected , but found ;. Typing the missing ) clears all markers.
• Scrolled down to line 11: before, there was no sign of the error; now the red tick on the scrollbar stays visible.

New unit tests check the result for valid code, a syntax error (line and column), an unclosed block, and that throw new Error(...) isn't executed.

Dropped from the original plan

• An "unsynced changes" indicator: edits sync every second and on close, so it would show for under a second and doesn't fix a real problem.
• A "bound member" label next to the card slot: the card's tooltip already shows Member: ..., and there is already a check mark next to the slot.

Testing

• ./gradlew build passes, including the new unit tests.
• ./gradlew runGameTestServer: all 22 tests pass.
• I didn't add a game test for the server-side debounce, because it needs an open container with a real player connection to observe the packet. The checker itself is covered by the unit tests.

🤖 Generated with Claude Code

https://claude.ai/code/session_018MRyTdV3fSV5Q5NPGep4q9

[coveralls]

Coverage Report for CI Build 39131969099

Coverage decreased (-1.1%) to 43.008%

Details

• Coverage decreased (-1.1%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 542 coverage regressions across 6 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

542 previously-covered lines in 6 files lost coverage.

File	Lines Losing Coverage	Coverage
org/cyclops/integratedscripting/client/gui/component/input/WidgetTextArea.java	272	0.0%
org/cyclops/integratedscripting/client/gui/container/ContainerScreenTerminalScripting.java	156	0.0%
org/cyclops/integratedscripting/inventory/container/ContainerTerminalScripting.java	94	23.53%
org/cyclops/integratedscripting/core/language/LanguageHandlerJavaScript.java	18	57.14%
org/cyclops/integratedscripting/api/language/ILanguageHandler.java	1	0.0%
org/cyclops/integratedscripting/proxy/CommonProxy.java	1	87.5%

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Coverage Stats

Relevant Lines:	3349
Covered Lines:	1582
Line Coverage:	47.24%
Relevant Branches:	1371
Covered Branches:	448
Branch Coverage:	32.68%
Branches in Coverage %:	Yes
Coverage Strength:	22.32 hits per line

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💛 - Coveralls

[rubensworks]

Replaced by #87: same changes, rebased as one standalone commit.

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Generated by Claude Code