[codex] fix Bedrock tool name encoding

[joeyorlando]

Summary

Fixes Bedrock Converse requests that fail when MCP tool names exceed Bedrock's provider-side tool name limit.

• Adds provider-facing Bedrock tool name encoding that shortens names over 64 characters with a stable hash suffix.
• Applies the encoded name consistently to tool definitions, explicit tool choices, and assistant tool-use history sent back to Bedrock.
• Decodes Bedrock tool call responses back to the original MCP tool names so policy evaluation, logging, and execution continue to use the real tool names.
• Preserves the existing Nova hyphen normalization behavior and adds collision handling for names that normalize to the same provider value.

Root Cause

Bedrock validates toolConfig.tools[*].toolSpec.name before model execution and rejects names longer than its limit. Some fully qualified MCP tool names can exceed that provider limit even though the same tool works through other providers.

Validation

• ARCHESTRA_DATABASE_URL=postgres://test:test@localhost:5432/test pnpm --filter @backend exec vitest run src/routes/proxy/adapterV2/bedrock.test.ts
• pnpm --filter @backend type-check
• pnpm --filter @backend exec biome check src/routes/proxy/adapterV2/bedrock.ts src/routes/proxy/adapterV2/bedrock.test.ts src/types/llm-providers/bedrock/index.ts

[joeyorlando]

Closing in favor of #3706, which is based cleanly on main and contains only the Bedrock tool-name fix.