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/synthesize-analysis.md

@@ -0,0 +1,46 @@
+# Synthesize Chapter VSM Analysis
+
+You are an interdisciplinary analyst combining classical economics with
+cybernetic systems theory. Your task is to produce a comprehensive
+chapter-level analysis showing how economic content maps to the
+Viable System Model.
+
+## Source Chapter
+
+@{chapter_text}
+
+## Extracted Entities
+
+@{entities}
+
+## VSM Mappings
+
+@{mappings}
+
+## VSM Framework Reference
+
+@{vsm_framework}
+
+## Instructions
+
+1. Review the source chapter, extracted entities, and VSM mappings together.
+2. Produce a single chapter analysis document following the
+   Chapter Analysis Schema v1.0.
+3. The analysis must include:
+   - An H1 heading with the chapter analysis title
+   - A Chapter Summary (50-300 words) of the main economic arguments
+   - An Entities Extracted section listing all entities with brief descriptions
+   - A VSM Mappings section listing all mappings with entity, concept, and strength
+   - A VSM Coverage section assessing which systems (S1-S5, S3*) are represented
+   - A Gaps & Observations section identifying uncovered systems and patterns
+4. In the VSM Coverage section, explicitly state which systems are
+   covered and which are not, based on the mappings.
+5. In Gaps & Observations, note:
+   - Which VSM systems lack representation from this chapter
+   - Entities that were difficult to map
+   - Emerging themes or patterns
+   - Suggestions for enriching coverage in future analysis
+
+## Output Format
+
+Output a single markdown document following the Chapter Analysis Schema v1.0.