feat: add config module and agent setup for migration

- Add config module from backup (loader, accessor, migration)
- Add agent reference cards for token-efficient migration
- Add migration knowledge base and instructions
- Ready to start systematic config-driven migration

.migration/knowledge/AGENT_INSTRUCTIONS.md

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+# Agent Instructions Template (Token-Efficient)
+
+## Syntax Fixer Agent
+```markdown
+TASK: Fix syntax errors in FILE_PATH
+PATTERNS: See SYNTAX_FIX_CARD.md
+OUTPUT: {"status": "fixed", "changes": N, "test_passed": bool}
+TEST: nu --ide-check FILE_PATH
+```
+
+## ENV Migrator Agent
+```markdown
+TASK: Replace ENV vars in FILE_PATH
+MAPPING: See ENV_MAPPING_CARD.md
+KEEP: PROVISIONING_ARGS, PROVISIONING_OUT, NOW, CURRENT_*
+OUTPUT: {"status": "migrated", "replacements": N}
+```
+
+## Validator Agent
+```markdown
+TASK: Test FILE_PATH works
+COMMANDS: nu --ide-check FILE_PATH
+OUTPUT: {"syntax_valid": bool, "errors": []}
+```
+
+## File Analyzer Agent
+```markdown
+TASK: Find issues in FILE_PATH
+FIND: syntax errors, env refs, hardcoded paths
+OUTPUT: {"syntax_errors": [], "env_refs": [], "paths": []}
+```
+
+## Token Budget
+- Single file: ~500-1000 tokens
+- Pattern reference: ~200 tokens
+- Instructions: ~300 tokens
+- Total per agent: ~1000-1500 tokens

.migration/knowledge/ENV_MAPPING_CARD.md

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+# ENV → Accessor Mapping (Token-Efficient Reference)
+
+## Critical Mappings
+
+### Core Variables
+```nushell
+$env.PROVISIONING              → (get-base-path)
+$env.PROVISIONING_DEBUG         → (is-debug-enabled)
+$env.PROVISIONING_OUT           → (get-provisioning-out)
+$env.PROVISIONING_ARGS          → (get-provisioning-args)
+$env.PROVISIONING_MODULE        → (get-provisioning-module)
+$env.PROVISIONING_NAME          → (get-provisioning-name)
+```
+
+### Path Variables
+```nushell
+$env.PROVISIONING_PROVIDERS_PATH → (get-providers-path)
+$env.PROVISIONING_TASKSERVS_PATH → (get-taskservs-path)
+$env.PROVISIONING_TOOLS_PATH     → (get-tools-path)
+$env.PROVISIONING_TEMPLATES_PATH → (get-templates-path)
+```
+
+### Runtime Variables (Keep as ENV)
+```nushell
+$env.PROVISIONING_ARGS    # Command arguments - KEEP
+$env.PROVISIONING_OUT     # Output redirection - KEEP
+$env.NOW                  # Timestamps - KEEP
+$env.CURRENT_*            # Context variables - KEEP
+```
+
+## Usage Pattern
+```nushell
+# Always wrap in parentheses
+let value = ((get-function-name) | default "fallback")
+```

.migration/knowledge/SYNTAX_FIX_CARD.md

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+# Syntax Fix Patterns (Token-Efficient Reference)
+
+## Critical Patterns to Fix
+
+### 1. Function Call Parentheses
+```nushell
+# BROKEN
+$"(get-provisioning-args)? | default "") "
+
+# FIXED
+((get-provisioning-args) | default "")
+```
+
+### 2. Command Parentheses
+```nushell
+# BROKEN
+^$"(get-provisioning-name))" -mod server
+
+# FIXED
+^(get-provisioning-name) -mod server
+```
+
+### 3. Missing Function Calls
+```nushell
+# BROKEN
+let ops = $"(get-provisioning-args)? | default "") "
+
+# FIXED
+let ops = ((get-provisioning-args) | default "")
+```
+
+## Testing Command
+```bash
+nu --ide-check FILE_PATH
+```
+
+## Success Pattern
+All function calls must be wrapped in parentheses when used in expressions.