chore: add meta.yaml for PACEngine and arithmetic notes directories

Mewtwo Phase 0 codebase readiness — semantic navigation metadata.

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

Author: Peter Groom

foundational/arithmetic/PACEngine/meta.yaml

@@ -0,0 +1,27 @@
+schema_version: '2.0'
+directory_name: PACEngine
+description: >
+  Core PAC conservation mathematics engine. Implements f(parent) = Σf(children)
+  conservation law, geometric SEC operators, and validation infrastructure.
+  Contains the primary computational substrate for PAC theory — conservation
+  testing, data collection, integration modules, and visualization tools.
+semantic_scope:
+  - pac-conservation
+  - mathematical-engine
+  - conservation-law
+  - geometric-SEC
+  - validation
+files:
+  - pac_engine.py
+  - collect_data.py
+  - test_conservation.py
+  - README.md
+child_directories:
+  - core
+  - docs
+  - experiments
+  - integration
+  - modules
+  - results
+  - validation
+  - visualization

foundational/arithmetic/notes/meta.yaml

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+schema_version: '2.0'
+directory_name: notes
+description: >
+  Research notes and working documents for PAC arithmetic foundations.
+  Informal analysis, derivation sketches, and theoretical exploration.
+semantic_scope:
+  - research-notes
+  - pac-arithmetic
+  - working-documents
+child_directories:
+  - PAC