feat: add bump-version.sh script for version management

Automates version bumps across all version source files:
- Cargo.toml (PRIMARY - workspace.package.version)
- debian/changelog (prepend new entry)
- debian/control (update Version field)
- scripts/build-package.sh (update VERSION variable)
- frontend/package.json (update version field)
- Stale references check after bump

Usage: ./scripts/bump-version.sh <new_version> <old_version>

migrations/006_host_patch_data_unique.sql

@@ -0,0 +1,19 @@
+-- Migration 006: Add UNIQUE constraint on host_id in host_patch_data
+-- Clean up duplicate rows (keep latest polled_at per host) before adding constraint.
+
+-- Step 1: Delete duplicate rows, keeping only the most recent poll per host
+DELETE FROM host_patch_data a
+USING host_patch_data b
+WHERE a.host_id = b.host_id
+  AND a.polled_at < b.polled_at;
+
+-- Step 2: Add UNIQUE constraint on host_id (idempotent)
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint WHERE conname = 'host_patch_data_host_id_key'
+  ) THEN
+    ALTER TABLE host_patch_data
+      ADD CONSTRAINT host_patch_data_host_id_key UNIQUE (host_id);
+  END IF;
+END $$;