Add issue identifiers, activity run tracking, and migration inspection

Add issuePrefix/issueCounter to companies and issueNumber/identifier to issues
for human-readable issue IDs (e.g. PAP-42). Add runId to activity_log for
linking activity to heartbeat runs. Rework DB client to support migration
state inspection and interactive pending migration prompts at startup.
Add reopen option to issue comments validator.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/db/src/index.ts

@@ -1,6 +1,9 @@
 export {
   createDb,
   ensurePostgresDatabase,
+  inspectMigrations,
+  applyPendingMigrations,
+  type MigrationState,
   migratePostgresIfEmpty,
   type MigrationBootstrapResult,
   type Db,