refactor(constants): enforce ModelConstants — replace hardcoded model strings (#3528)

[mrveiss]

Summary

Replaces 40+ hardcoded model name strings across 14 files with constants from constants/model_constants.py. Consolidates three duplicate MODEL_PRICING dictionaries into a single authoritative source.

model_constants.py additions

• Explicit constants for all OpenAI/Anthropic/Google/local model names (OPENAI_GPT4, OPENAI_GPT35_TURBO, ANTHROPIC_CLAUDE3_OPUS_DATED, GOOGLE_GEMINI_PRO_VISION, etc.)
• Substring marker constants EXPENSIVE_MODEL_MARKER_OPUS, EXPENSIVE_MODEL_MARKER_GPT4
• Three canonical pricing dicts: MODEL_PRICING_PER_1M_TOKENS, MODEL_PRICING_PER_1K_TOKENS, MODEL_COSTS_PER_1M_TOKENS

Files updated

File	Change
constants/model_constants.py	+120 lines of new constants + pricing dicts
services/llm_cost_tracker.py	MODEL_PRICING dict → MODEL_PRICING_PER_1M_TOKENS import
modern_ai_integration.py	7 hardcoded vision/model strings → named constants
llm_multi_provider.py	Fallback + default + model list strings → constants
llm_interface_pkg/providers/openai_provider.py	"gpt-3.5-turbo" fallback → OPENAI_GPT35_TURBO
models/settings.py	Field default → OPENAI_GPT35_TURBO
api/analytics_llm_patterns.py	EXPENSIVE_MODELS set + MODEL_COSTS dict + substring checks → constants
code_intelligence/llm_pattern_analysis/calculators.py	Both pricing dicts + fallback key → constants
code_intelligence/llm_pattern_analysis/data_models.py	expensive_markers list → constants
llm_providers/openai_provider.py	Model list + fallback defaults → constants
llm_providers/anthropic_provider.py	4 of 6 model list entries → constants
services/analytics_service.py	Substring checks → marker constants
api/llm_providers.py	Docstring example → generic reference

Closes #3528

[github-actions]

✅ SSOT Configuration Compliance: Passing

🎉 No hardcoded values detected that have SSOT config equivalents!