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/schemas/vsm-mapping-schema-v1.0.md

@@ -0,0 +1,41 @@
+# VSM Mapping Schema v1.0
+
+Schema definition for entity-to-VSM concept mapping documents.
+
+## Required Sections
+
+### Economic Entity Reference
+The name and identifier of the economic entity being mapped.
+Must correspond to an existing entity in the entities collection.
+
+### VSM Concept Reference
+The name and identifier of the VSM concept being mapped to.
+Must correspond to an existing concept in the concepts collection.
+
+### Mapping Rationale
+A detailed explanation of why this economic entity maps to this VSM concept.
+Should reference specific properties of both the entity and the concept
+that justify the mapping (minimum 30 words).
+
+### Mapping Strength
+One of:
+- **Strong**: Direct structural or functional correspondence
+- **Moderate**: Clear conceptual parallel with some differences
+- **Weak**: Loose analogy or partial overlap
+
+## Optional Sections
+
+### Counter-arguments
+Reasons why this mapping might be contested or why the entity
+might not fit the VSM concept perfectly.
+
+### Alternative Mappings
+Other VSM concepts this entity could plausibly map to,
+with brief rationale for each alternative.
+
+## Validation Rules
+
+1. The document MUST contain an H1 heading in the format "Entity Name -> VSM Concept Name".
+2. The document MUST contain all four required sections: Economic Entity Reference, VSM Concept Reference, Mapping Rationale, Mapping Strength.
+3. The Mapping Strength MUST be one of: Strong, Moderate, Weak.
+4. The document MUST reference both an economic entity and a VSM concept.