[recipes] Make schema-aware routing SQL idempotent

[Humestone]

Summary

• update the schema-aware-routing README setup SQL so it uses create table if not exists for recipe tables
• extend an existing canonical thoughts table with domain, status, and source via alter table ... add column if not exists
• add supporting indexes for the recipe-specific thoughts columns and clarify the SQL is safe after the canonical getting-started setup

Why

The current README tells users to create thoughts from scratch. That fails or conflicts for users who already followed the canonical OB1 getting-started SQL. This keeps the recipe aligned with OB1's shared thoughts table contract while preserving the standalone setup path.

Verification

• reviewed the README SQL block against docs/01-getting-started.md
• rg check for non-idempotent table creation in the edited block
• git diff --check

Notes

This PR only updates the setup SQL embedded in the README on current main; it does not add missing scaffold files or new runtime behavior.

Related to #262.

[alanshurafa]

Thanks for the contribution. Making the recipe SQL idempotent is the right direction — create table if not exists plus alter ... add column if not exists lets it run cleanly after the canonical OB1 setup.

One thing to resolve before this is ready: the recipe adds status text default 'active' to the shared thoughts table, but schemas/workflow-status already declares status on thoughts as text default null and uses it for kanban-style task/idea state. Since add column if not exists skips when the column is already present, both the default and the meaning of status would depend on which setup ran first. Could you confirm whether this recipe's status is the same concept? If it is, matching default null keeps the two consistent; if it is a distinct routing concept, a different column name would avoid the collision. (domain and source look recipe-specific — no conflict there.)

Minor: the alter ... add column if not exists lines for metadata, created_at, and updated_at duplicate columns the create table block above already declares — worth trimming for clarity.

Recommend author refresh once the status question is settled.

— Alan (community reviewer; non-binding)