feat: add per-tool customerContext parameter for dynamic customer scoping

[venotar]

Summary

• Adds customerContext as an optional string parameter to all 36 MCP tool schemas, enabling clients to dynamically scope API calls to a specific customer without relying on the CUSTOMER_CONTEXT environment variable
• Inline JSON tools use a shared customerContextProperty spread; Zod-based tools get automatic injection via zodToMcpInputSchema()
• Parameter is injected into JSON Schema output only (not Zod parsing), preventing leakage into API request bodies
• Cross-cutting test validates all registered tools expose customerContext with correct type and description

Refs #114

Test plan

• All 447 existing tests pass across 26 test files
• New customerContextSchema.test.ts verifies all 36 tools have customerContext as optional string
• Updated schema.test.ts accounts for injected property without breaking existing assertions
• changeCustomer tool (which has its own customerContext with different semantics) is not overwritten

🤖 Generated with Claude Code

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Note

Medium Risk
Broad, cross-cutting schema changes across many MCP tools may affect client tool discovery/validation and request shaping, though the parameter is additive and covered by new tests.

Overview
Adds a new optional customerContext string parameter to MCP tool inputSchemas to let clients scope API calls per request rather than relying on a global env var.

Centralizes the schema definition via CUSTOMER_CONTEXT_DESCRIPTION/customerContextProperty for hand-written schemas, and updates zodToMcpInputSchema() to inject customerContext into generated JSON Schema output without changing Zod parsing.

Adds/updates tests to enforce consistent customerContext presence/description across tools and to relax schema-structure comparisons to account for the injected property.

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