Preserve non-param template helpers

[gnzjgo]

Summary

Fixes a regression from param metadata generation where non-param template helpers could receive Tinybird parameter metadata.

• Only inject default/required/description metadata into typed Tinybird parameter functions such as String(...), DateTime(...), Int32(...), etc.
• Preserve helper calls such as split_to_array(siteIds) unchanged.
• Preserve column(orderBy) behavior while still allowing its supported default positional argument.
• Adds regression coverage for optional/described params used with split_to_array(...) and column(...).

Template function coverage

The generator uses an allowlist for metadata injection. Only documented transform type functions receive default, required, or description metadata:

• Boolean, Date, DateTime, DateTime64
• Float32, Float64
• Int8, Int16, Int32, Int64, Int128, Int256
• UInt8, UInt16, UInt32, UInt64, UInt128, UInt256
• String, Array

Everything else from the template-functions reference is preserved as written, including helpers like split_to_array(...), sql_and(...), and other non-transform helpers. column(...) is handled separately because Tinybird supports its positional default argument, but not required= or description= keyword args.

Problem

This TypeScript:

params: {
  siteIds: p.string().optional().describe("Comma-separated list of framerSiteId. Only used for test isolation"),
},
sql: `{{ split_to_array(siteIds) }}`,

could be generated as:

{{ split_to_array(siteIds, required=False, description="Comma-separated list of framerSiteId. Only used for test isolation") }}

Tinybird rejects that because split_to_array does not accept those keyword args:

split_to_array() got an unexpected keyword argument 'required'

How to test

export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"
nvm use 20
pnpm vitest run src/generator/pipe.test.ts
pnpm typecheck