Use profile relationship connector for event builds

[RANGROO]

Problem

Stobe's manual Build from Events endpoint ignored the NPC profile's configured relationship connector whenever the legacy RELLLM_CONNECTOR global was absent. It fell back to the first connector instead.

For the reported Herika failure, that selected OpenRouter Default rather than the Player Faction profile's Gemini 2.5 Flash relationship connector. OpenRouter Auto routed the 9,016-token prompt to DeepSeek V4 Flash, which used the full 1,024-token completion on reasoning and returned empty content.

Change

• Resolve the existing NPC-specific relationship connector used by live affinity updates.
• Respect per-NPC overrides and the NPC/default profile's relationship_connector.
• Retain the legacy global override when present.
• Fall back to the profile response connector, then the default connector.

This is separate from #90, which limited the bulk migration scope. This PR fixes the manual per-NPC Build from Events action.

Compatibility

No schema or configuration migration is required.

HerikaServer already loads its global relationship connector for this endpoint. DialecticServer independently bootstraps its global connector, so no sibling port is needed.

Validation

• php -l ext/relationship_system/analyze_relationships.php
• STOBE_DB_NAME=stobe_test php tests/relationship_system_regression.php
• git diff --check origin/unstable...HEAD
• Read-only database verification: Herika resolves the Player Faction profile's connector 0.7.5 Update #4, Gemini 2.5 Flash (google/gemini-2.5-flash).

Deployment

Not deployed.

Limits

No live LLM request was made because it would incur an external request and persist relationship data. No browser or in-game validation was performed.