WPB-22811 migrate conversation codes table to postgres

[battermann]

https://wearezeta.atlassian.net/browse/WPB-22811

backendA=# EXPLAIN select value, conversation, password, GREATEST(0, FLOOR(EXTRACT(EPOCH FROM (expires_at - now ())))) AS ttl_sec from conversation_codes where key = '8UZlQIPzoV6Rw_fADs4p' AND scope = 1 AND expires_at > now ();
                                             QUERY PLAN
----------------------------------------------------------------------------------------------------
 Index Scan using conversation_codes_pkey on conversation_codes  (cost=0.15..8.19 rows=1 width=112)
   Index Cond: ((key = '8UZlQIPzoV6Rw_fADs4p'::text) AND (scope = 1))
   Filter: (expires_at > now())
(3 rows)

Checklist

• Add a new entry in an appropriate subdirectory of changelog.d
• Read and follow the PR guidelines

[Copilot]

Pull request overview

This PR migrates the conversation codes table from Cassandra to PostgreSQL, following the same pattern used for the conversation table migration. The implementation includes a PostgreSQL store, dual-write capability during migration, and a background worker to migrate existing data.

Changes:

• Added PostgreSQL implementation for conversation codes storage with appropriate schema and indexes
• Implemented dual-write pattern to write to both Cassandra and PostgreSQL during migration
• Created background worker migration task to migrate existing conversation codes from Cassandra to PostgreSQL
• Updated configuration to allow choosing storage backend (Cassandra, PostgreSQL, or migration mode)

Reviewed changes

Copilot reviewed 36 out of 36 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
postgres-schema.sql	Added conversation_codes table schema and indexes
libs/wire-subsystems/postgres-migrations/20260115150600-conversation-codes.sql	PostgreSQL migration script creating conversation_codes table
libs/wire-subsystems/src/Wire/CodeStore/Postgres.hs	PostgreSQL implementation of CodeStore operations
libs/wire-subsystems/src/Wire/CodeStore/DualWrite.hs	Dual-write interpreter for migration phase
libs/wire-subsystems/src/Wire/CodeStore/Migration.hs	Migration logic to copy codes from Cassandra to PostgreSQL
libs/wire-subsystems/src/Wire/Migration.hs	Shared migration utilities extracted from conversation migration
libs/wire-subsystems/src/Wire/CodeStore/Scope.hs	Added PostgreSQL marshalling instances for Scope
libs/wire-api/src/Wire/API/PostgresMarshall.hs	Added marshalling instances for Code.Key, Code.Value, and Password
services/galley/src/Galley/App.hs	Added interpreter selection based on configuration
services/background-worker/src/Wire/PostgresMigrations.hs	Added conversation codes migration worker
services/background-worker/src/Wire/BackgroundWorker.hs	Integrated conversation codes migration into worker lifecycle
integration/test/Test/Migration/ConversationCodes.hs	Integration tests for conversation codes migration
charts/*/values.yaml	Added conversationCodes configuration option
docs/src/developer/reference/config-options.md	Updated documentation for migration configuration

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[akshaymankar]

Thanks for the docs, they look good. I'd say let's move the instances to the right place, other feedback is not so important.

[akshaymankar]