fix: resolve empty/wrong domain classifications

[yehudit1987]

Fix domain classifier returning empty or incorrect categories.

Changes:

• Add fallback to "other" when confidence < threshold (classifier.go)
• Add ModernBERT fallback when CandleBERT fails
• Add PII type translation: class_X → DATE_TIME (mapping.go)
• Include category header in PII/cache responses (response.go)
• Auto-load supplement dataset from HuggingFace (ft_linear.py)
• Update Helm defaults to use trained model from LLM-Semantic-Router
• Move test cases to JSON files with go:embed
• Remove CRD-incompatible tests from dynamic-config profile

HuggingFace resources (LLM-Semantic-Router org):

• New trained model: category_classifier_modernbert-base_trained_model
• New supplement dataset: category-classifier-supplement (653 examples)

Resolves #714

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[github-actions]

👥 vLLM Semantic Team Notification

The following members have been identified for the changed files in this PR and have been automatically assigned:

📁 deploy

Owners: @rootfs, @Xunzhuo
Files changed:

• deploy/helm/semantic-router/values.yaml
• deploy/kubernetes/aibrix/semantic-router-values/values.yaml

📁 e2e

Owners: @Xunzhuo
Files changed:

• e2e/profiles/ai-gateway/values.yaml
• e2e/profiles/dynamic-config/profile.go
• e2e/profiles/dynamic-config/values.yaml
• e2e/profiles/llm-d/values.yaml
• e2e/profiles/production-stack/values.yaml
• e2e/profiles/routing-strategies/values.yaml
• e2e/testcases/decision_fallback.go
• e2e/testcases/plugin_config_variations.go
• e2e/testcases/testdata/decision_fallback_cases.json
• e2e/testcases/testdata/domain_classify_cases.json
• e2e/testcases/testdata/plugin_config_cases.json

📁 Root Directory

Owners: @rootfs, @Xunzhuo
Files changed:

• perf/testdata/baselines/cache.json
• perf/testdata/baselines/classification.json
• perf/testdata/baselines/decision.json
• perf/testdata/baselines/extproc.json

📁 src

Owners: @rootfs, @Xunzhuo, @wangchen615
Files changed:

• src/semantic-router/pkg/classification/classifier.go
• src/semantic-router/pkg/classification/mapping.go
• src/semantic-router/pkg/classification/mcp_classifier.go
• src/semantic-router/pkg/config/config.go
• src/semantic-router/pkg/extproc/req_filter_cache.go
• src/semantic-router/pkg/extproc/req_filter_pii.go
• src/semantic-router/pkg/utils/http/response.go
• src/semantic-router/pkg/utils/http/response_test.go
• src/training/classifier_model_fine_tuning/ft_linear.py

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This comment was automatically generated based on the OWNER files in the repository.