Add outlook schema transition guide

docs/roadmap/outlook-schema-transition.md

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+# SPC Outlook Postgres Schema Transition
+
+## Purpose
+
+This document describes how to reset existing Postgres outlook tables from the
+`weather.outlook.v1` storage shape to the `weather.outlook.v2` compatible
+storage shape.
+
+Updated `weatherfeeder` versions create outlook tables with run-level
+discussion storage. Existing databases that already contain the old outlook
+table family need a manual reset because the Postgres sink creates tables with
+`CREATE TABLE IF NOT EXISTS`.
+
+## Scope
+
+This reset drops only the outlook table family and lets updated `weatherfeeder`
+recreate it:
+
+- `outlook_discussions`
+- `outlooks`
+- `outlook_runs`
+
+Other weather tables are not affected.
+
+## Warning
+
+These commands delete stored SPC outlook history. Existing `weather.outlook.v1`
+outlook rows are intentionally removed. Downstream readers should be updated
+intentionally for the new outlook shape.
+
+## Deployment Order
+
+1. Stop `weatherfeeder`.
+2. Drop the existing outlook tables.
+3. Deploy updated `weatherfeeder`.
+4. Start `weatherfeeder` so the Postgres sink recreates the new outlook tables.
+5. Deploy updated downstream consumers such as `weatherapi`.
+
+## Reset SQL
+
+```sql
+DROP TABLE IF EXISTS outlook_discussions;
+DROP TABLE IF EXISTS outlooks;
+DROP TABLE IF EXISTS outlook_runs;
+```
+
+## Verification SQL
+
+Before or after the updated daemon starts, this query shows which outlook tables
+exist:
+
+```sql
+SELECT table_name
+FROM information_schema.tables
+WHERE table_name IN ('outlook_runs', 'outlooks', 'outlook_discussions')
+ORDER BY table_name;
+```
+
+After the updated daemon has started and recreated the tables, verify the new
+run column:
+
+```sql
+SELECT column_name, is_nullable, data_type
+FROM information_schema.columns
+WHERE table_name = 'outlook_runs'
+  AND column_name = 'discussion_count';
+```
+
+Verify the discussion table indexes:
+
+```sql
+SELECT indexname
+FROM pg_indexes
+WHERE tablename = 'outlook_discussions'
+ORDER BY indexname;
+```
+
+Verify that legacy polygon-level prose columns are gone from `outlooks`:
+
+```sql
+SELECT column_name
+FROM information_schema.columns
+WHERE table_name = 'outlooks'
+  AND column_name IN ('headline', 'summary', 'discussion');
+```
+
+The final query should return zero rows.