feat: Update to production model stack and fix remaining inconsistencies

## Model Stack Updates (User's Actual Models)

Updated all documentation to reflect production models:
- Claude Opus 4.5 (primary reasoning)
- GPT 5.1 Codex max (code generation specialist)
- Gemini 3 Pro/Flash (multimodal, fast inference)
- Qwen3-235B (cost-effective, self-hostable)
- DeepSeek V3.2 (self-hosted, open weights)

### Files Updated:
- ADR-004: Full model groups, failover chains, cost tables
- ADR-007: Code example with correct model identifiers
- ADR-012: Cost tracking with new model prices
- ARCHITECTURE.md: Model groups, failover diagram
- IMPLEMENTATION_ROADMAP.md: External services list

## Architecture Diagram Updates

- Added LangGraph Runtime to orchestration layer
- Added technology labels (Type-Instance, transitions)

## Self-Hostability Table Expanded

Added entries for:
- LangGraph (MIT)
- transitions (MIT)
- DeepSeek V3.2 (MIT)
- Qwen3-235B (Apache 2.0)

## Metric Alignments

- Response time: Split into API (<200ms) and Agent (<10s/<60s)
- Cost per project: Adjusted to $100/sprint for Opus 4.5 pricing
- Added concurrent projects (10+) and agents (50+) metrics

## Infrastructure Updates

- Celery workers: 4-8 instances (was 2-4) across 4 queues
- MCP servers: Clarified Phase 2 + Phase 5 deployment
- Sync interval: Clarified 60s fallback + 15min reconciliation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/adrs/ADR-012-cost-tracking.md

@@ -154,22 +154,24 @@ GROUP BY project_id, DATE(timestamp);
 
 ### Cost Model Prices
 
-| Model | Input ($/1M) | Output ($/1M) |
-|-------|-------------|---------------|
-| Claude 3.5 Sonnet | $3.00 | $15.00 |
-| Claude 3 Haiku | $0.25 | $1.25 |
-| GPT-4 Turbo | $10.00 | $30.00 |
-| GPT-4o Mini | $0.15 | $0.60 |
-| Ollama (local) | $0.00 | $0.00 |
+| Model | Input ($/1M) | Output ($/1M) | Notes |
+|-------|-------------|---------------|-------|
+| Claude Opus 4.5 | $15.00 | $75.00 | Highest reasoning capability |
+| GPT 5.1 Codex max | $12.00 | $60.00 | Code generation specialist |
+| Gemini 3 Pro | $3.50 | $10.50 | Strong multimodal |
+| Gemini 3 Flash | $0.35 | $1.05 | Fast inference |
+| Qwen3-235B | $2.00 | $6.00 | Cost-effective (or $0 self-hosted) |
+| DeepSeek V3.2 | $0.00 | $0.00 | Self-hosted, open weights |
 
 ### Cost Optimization Strategies
 
 | Strategy | Savings | Implementation |
 |----------|---------|----------------|
 | Semantic caching | 15-30% | Redis cache for repeated queries |
-| Model cascading | 60-80% | Start with Haiku, escalate to Sonnet |
+| Model cascading | 60-80% | Start with Gemini Flash, escalate to Opus |
 | Prompt compression | 10-20% | Remove redundant context |
-| Local fallback | 100% for some | Ollama for simple tasks |
+| Self-hosted fallback | 100% for some | DeepSeek V3.2/Qwen3 for non-critical tasks |
+| Task-appropriate routing | 40-60% | Route code tasks to GPT 5.1 Codex, simple to Flash |
 
 ## Consequences