Add profile LLM response tiers

[RANGROO]

Summary

• Add Standard, Fast, Powerful, and Experimental LLM connector slots to Stobe profiles.
• Select the active response tier globally through the hidden stobe_profile_model conf_opts value, matching CHIM's numeric 1-4 slot behavior.
• Keep profile UI limited to connector assignments; no response-mode selector is exposed.
• Preserve Stobe's dedicated Autochat, Background Life, Diary, Memory, Dynamic Profile, Relationship, and TTS connectors.

Compatibility

• Backfill Standard from each profile's existing response_connector.
• Keep response_connector synchronized with Standard for existing integrations.
• Fall back to Standard, then the legacy response connector, when the globally selected tier is unavailable.
• Strip obsolete LLM_RESPONSE_MODE profile metadata during migration and future profile saves/imports.
• Update profile save, clone, import/export, Quickstart, Player2 setup, connector deletion checks, and connector tests.

Database

• Add four nullable connector columns with ON DELETE SET NULL foreign keys.
• Add idempotent tier migration core_profiles:202607290301.
• Add idempotent global-mode migration core_profiles:202607290302, defaulting missing or invalid global values to Standard (1) without overwriting valid values.

Validation

• PHP lint on all seven changed PHP files.
• git diff --check.
• Fresh UTF-8 disposable database schema application.
• Upgrade from current origin/unstable schema on a disposable database.
• Upgrade from a database that had already applied migration 202607290301.
• tests/chat_flow_regression.php.
• tests/startup_runtime_regression.php.
• tests/database_upgrade_regression.php.
• tests/conversation_context_regression.php.
• Focused routing probes for global tier selection, Standard fallback, invalid-slot fallback, and unchanged legacy response fallback.
• Desktop and 390px browser verification: four connector slots render, the response-mode selector is absent, and no horizontal overflow is introduced.

Local deployment

• Deployed commit 6e1f4b7dce4d23ec04d5d159e0af674e0a394b2f to /var/www/html/StobeServer.
• Deployed files match the source commit byte-for-byte.
• Live database reports stobe_profile_model=1, migration core_profiles:202607290302, four tier columns, and zero obsolete metadata rows.
• health.php and ui/profiles.php return HTTP 200.

Related PR

• Add in-game response mode controls STOBE#11 adds the in-game HUD display and chatbox response-mode selector.

Limits

• Not tested in-game with a live LLM response.