feat(llm): add LLM integration module with OpenRouter and Claude Code adapters

Implements markitect/llm/ package with concrete LLMAdapter implementations:
- OpenRouterAdapter: HTTP via urllib with retry/backoff on 429/5xx
- ClaudeCodeAdapter: subprocess-based Claude CLI with stdin piping
- Factory pattern: create_adapter("openrouter") or create_adapter("claude-code")
- API key resolution chain: constructor > env var > project-root key file
- 42 unit tests, 2 integration tests (gated on API key / CLI availability)

Also adds the infospace-with-history example with Wealth of Nations VSM
analysis pipeline, templates, schemas, source chapters, and processed
output for chapters 1-2. process_chapters.py now supports --provider
and --model flags for automatic LLM-driven processing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

examples/infospace-with-history/templates/assess-metrics.md

@@ -0,0 +1,38 @@
+# Assess Completeness & Consistency Metrics
+
+You are a quality assurance analyst evaluating the completeness and
+consistency of a growing information space that maps classical economics
+to the Viable System Model.
+
+## All Chapter Analyses
+
+@{all_analyses}
+
+## VSM Framework Reference
+
+@{vsm_framework}
+
+## Instructions
+
+1. Review all chapter analyses produced so far.
+2. Compute the following completeness metrics:
+   - **VSM Concept Coverage**: Percentage of VSM concepts (S1, S2, S3, S3*, S4, S5,
+     plus key concepts like recursion, variety, requisite variety, autonomy,
+     viability, attenuation/amplification, algedonic signals) that have at
+     least one mapping. List covered and uncovered concepts.
+   - **Chapter Coverage**: Percentage of source chapters processed.
+   - **Entity Count**: Total number of distinct economic entities extracted.
+   - **Mapping Count**: Total number of entity-to-VSM mappings created.
+3. Compute the following consistency metrics:
+   - **Terminology Consistency** (score 0.0-1.0): Whether the same economic
+     concept is named consistently across all documents. Flag inconsistencies.
+   - **Cross-reference Integrity** (score 0.0-1.0): Whether all entity references
+     in mappings point to existing entities. Flag broken references.
+   - **Schema Compliance** (percentage): Percentage of output documents that
+     contain all required sections per their respective schemas.
+4. Produce a metrics report summarizing the current state of the information space.
+
+## Output Format
+
+Output a single markdown document with sections for each metric category:
+Completeness Metrics, Consistency Metrics, and Recommendations.