Phase 4: Drop legacy entity tables

This completes the migration to the unified entity model by removing
the deprecated repositories, artifacts, and pull_requests tables.

## Changes

### Database Migration
- Add migration 000114 to drop legacy tables (repositories, artifacts, pull_requests)
- All data now stored in entity_instances and properties tables
- Down migration recreates empty tables (data recovery requires backup)

### Code Cleanup
- Remove SQL query files: repositories.sql, artifacts.sql
- Remove generated code: repositories.sql.go, artifacts.sql.go
- Remove db.Repository, db.Artifact, db.PullRequest structs from models
- Remove legacy methods from querier and mocks
- Remove PBRepositoryFromDB converter (internal/repositories/db.go)

### Reminder Service
- Document stateless throttling approach using evaluation history
- No longer tracks reminder_last_sent timestamp
- Enables horizontal scaling and improves reliability
- Throttling based on MinElapsed check against actual evaluation times

### Test Updates
- Create EntityRepository test helper for entity-based repository tests
- Update all test files to use EntityRepository instead of db.Repository
- Remove legacy repositories_test.go
- Update mock fixtures to remove legacy struct parameters
- All tests passing with full race detection

## Migration Path

1. Deploy this code to staging/production
2. Create database backup (CRITICAL - migration is irreversible)
3. Run migration to drop legacy tables
4. Monitor for errors
5. Optional: Run VACUUM to reclaim disk space

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: JAORMX

database/migrations/000114_drop_legacy_entity_tables.down.sql

@@ -0,0 +1,64 @@
+-- SPDX-FileCopyrightText: Copyright 2025 The Minder Authors
+-- SPDX-License-Identifier: Apache-2.0
+
+BEGIN;
+
+-- WARNING: This down migration recreates the table structure ONLY.
+-- It does NOT restore any data that was deleted when the tables were dropped.
+-- This is for structural rollback only - data recovery requires restoring from backup.
+
+-- Recreate repositories table
+CREATE TABLE repositories (
+    id UUID NOT NULL DEFAULT gen_random_uuid() PRIMARY KEY,
+    provider TEXT NOT NULL,
+    project_id UUID NOT NULL,
+    repo_owner TEXT NOT NULL,
+    repo_name TEXT NOT NULL,
+    repo_id INTEGER NOT NULL,
+    is_private BOOLEAN NOT NULL,
+    is_fork BOOLEAN NOT NULL,
+    webhook_id INTEGER,
+    webhook_url TEXT NOT NULL,
+    deploy_url TEXT NOT NULL,
+    clone_url TEXT NOT NULL,
+    default_branch TEXT,
+    license VARCHAR(255) DEFAULT 'unknown',
+    provider_id UUID,
+    reminder_last_sent TIMESTAMP,
+    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    FOREIGN KEY (project_id, provider) REFERENCES providers(project_id, name) ON DELETE CASCADE
+);
+
+ALTER TABLE repositories ADD CONSTRAINT unique_repo_id UNIQUE (repo_id);
+ALTER TABLE repositories ADD CONSTRAINT fk_repositories_provider_id FOREIGN KEY (provider_id) REFERENCES providers (id) ON DELETE CASCADE;
+
+-- Recreate artifacts table
+CREATE TABLE artifacts (
+    id UUID NOT NULL DEFAULT gen_random_uuid() PRIMARY KEY,
+    repository_id UUID NOT NULL REFERENCES repositories(id) ON DELETE CASCADE,
+    artifact_name TEXT NOT NULL,
+    artifact_type TEXT NOT NULL,
+    artifact_visibility TEXT NOT NULL,
+    project_id UUID,
+    provider_id UUID,
+    provider_name TEXT,
+    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
+);
+
+ALTER TABLE artifacts ADD CONSTRAINT fk_artifacts_project_id FOREIGN KEY (project_id) REFERENCES projects (id) ON DELETE CASCADE;
+ALTER TABLE artifacts ADD CONSTRAINT fk_artifacts_provider_id_and_name FOREIGN KEY (provider_id, provider_name) REFERENCES providers (id, name) ON DELETE CASCADE;
+
+-- Recreate pull_requests table
+CREATE TABLE pull_requests (
+    id UUID NOT NULL DEFAULT gen_random_uuid() PRIMARY KEY,
+    repository_id UUID NOT NULL REFERENCES repositories(id) ON DELETE CASCADE,
+    pr_number BIGINT NOT NULL,
+    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
+);
+
+CREATE UNIQUE INDEX pr_in_repo_unique ON pull_requests (repository_id, pr_number);
+
+COMMIT;

database/migrations/000114_drop_legacy_entity_tables.up.sql

@@ -0,0 +1,16 @@
+-- SPDX-FileCopyrightText: Copyright 2025 The Minder Authors
+-- SPDX-License-Identifier: Apache-2.0
+
+BEGIN;
+
+-- Drop legacy entity tables in correct order (respecting foreign keys)
+-- These tables have been fully replaced by the unified entity_instances and properties tables.
+-- All code has been migrated to use the new entity model.
+
+-- WARNING: This is a destructive operation. Ensure backups exist before running.
+
+DROP TABLE IF EXISTS pull_requests CASCADE;
+DROP TABLE IF EXISTS artifacts CASCADE;
+DROP TABLE IF EXISTS repositories CASCADE;
+
+COMMIT;

database/mock/fixtures/store.go

@@ -98,12 +98,12 @@ func WithSuccessfulGetFeatureInProject(
 }
 
 func WithSuccessfulUpsertPullRequest(
-	pullRequest db.PullRequest,
+	instance db.EntityInstance,
 ) func(*mockdb.MockStore) {
 	return func(mockStore *mockdb.MockStore) {
 		mockStore.EXPECT().
 			CreateOrEnsureEntityByID(gomock.Any(), gomock.Any()).
-			Return(db.EntityInstance{}, nil)
+			Return(instance, nil)
 	}
 }
 
@@ -131,7 +131,6 @@ func (m createOrEnsureEntityByIDParamsMatcher) Matches(x interface{}) bool {
 }
 
 func WithSuccessfulUpsertPullRequestWithParams(
-	pullRequest db.PullRequest,
 	instance db.EntityInstance,
 	entParams db.CreateOrEnsureEntityByIDParams,
 ) func(*mockdb.MockStore) {
@@ -144,15 +143,12 @@ func WithSuccessfulUpsertPullRequestWithParams(
 }
 
 func WithSuccessfulUpsertArtifact(
-	artifact db.Artifact,
+	instance db.EntityInstance,
 ) func(*mockdb.MockStore) {
 	return func(mockStore *mockdb.MockStore) {
-		mockStore.EXPECT().
-			UpsertArtifact(gomock.Any(), gomock.Any()).
-			Return(artifact, nil)
 		mockStore.EXPECT().
 			CreateOrEnsureEntityByID(gomock.Any(), gomock.Any()).
-			Return(db.EntityInstance{}, nil)
+			Return(instance, nil)
 	}
 }