Refactor: split long service files and centralize exception handling

[Copilot]

Codebase cleanup — several files grew past 500-600 lines. Split them into focused modules and eliminated repetitive try-catch boilerplate across controllers.

Server

• GlobalExceptionHandler (@ControllerAdvice) — centralizes exception→HTTP mapping (ResourceNotFoundException→404, IllegalArgumentException→400, IOException/RuntimeException→500). Removes ~160 lines of try-catch from ActivityController (591→434 lines).

// Before: every endpoint had this
try {
    ActivityResponse activity = activityService.getActivityById(id);
    return ResponseEntity.ok(activity);
} catch (Exception e) {
    logger.error("...", e.getMessage());
    return ResponseEntity.status(404).body(ErrorResponse.of(e.getMessage()));
}

// After: just the happy path
ActivityResponse activity = activityService.getActivityById(id);
return ResponseEntity.ok(activity);

• Split MarkdownToDocxService (632→270 lines) — extracted DocxHeaderFooterHelper (header/footer creation, logo, styled runs, field runs) and DocxTableHelper (Artikulationsschema table layout, column widths)

• Split ActivityService (673→491 lines) — extracted ActivityExtractionService for PDF upload, LLM metadata extraction, data normalization, and defaults

Client

• Split apiService.ts (521→106 lines) — extracted domain modules activityApiService.ts, historyApiService.ts, userApiService.ts. ApiService class remains as a re-exporting facade so all existing call sites are unaffected.

Test impact

All 62 server tests and 114 client tests pass unchanged (test setup updated for new constructors/injections).

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• jfrog-prod-use1-shared-virginia-main.s3.amazonaws.com
  • Triggering command: /usr/lib/jvm/temurin-21-jdk-amd64/bin/java /usr/lib/jvm/temurin-21-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /home/REDACTED/.m2/wrapper/dists/apache-maven-3.9.11/a2d47e15/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/home/REDACTED/.m2/wrapper/dists/apache-maven-3.9.11/a2d47e15/bin/m2.conf -Dmaven.home=/home/REDACTED/.m2/wrapper/dists/apache-maven-3.9.11/a2d47e15 -Dlibrary.jansi.path=/home/REDACTED/.m2/wrapper/dists/apache-maven-3.9.11/a2d47e15/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/LEARN-Hub/LEARN-Hub/server org.codehaus.plexus.classworlds.launcher.Launcher clean compile -q (dns block)
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java -Dfile.encoding=UTF-8 -Xms256M -Xss8M -Djdk.util.zip.disableZip64ExtraFieldValidation=true -Dsun.misc.unsafe.memory.access=allow --add-opens java.base/sun.reflect.annotation=ALL-UNNAMED -Xmx14576m -classpath /opt/hostedtoolcache/CodeQL/2.24.3/x64/codeql/java/tools/semmle-extractor-java.jar:/opt/hostedtoolcache/CodeQL/2.24.3/x64/codeql/java/tools/lombok-javac-extend.jar com.semmle.extractor.java.JavaExtractor --jdk-version 17 --javac-args @@@/tmp/codeql-scratch-21fe057196e5a270/dbs/java/log/ext/javac.args (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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