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/016_enrollment_requests.sql

@@ -0,0 +1,16 @@
+-- Migration: 016_enrollment_requests
+-- Description: Create enrollment_requests table for host self-enrollment
+
+CREATE TABLE enrollment_requests (
+    id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    machine_id      TEXT NOT NULL UNIQUE,
+    fqdn            TEXT NOT NULL,
+    ip_address      INET NOT NULL,
+    os_details      JSONB NOT NULL DEFAULT '{}',
+    polling_token   TEXT NOT NULL UNIQUE, -- Hashed polling token
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    expires_at      TIMESTAMPTZ NOT NULL DEFAULT NOW() + INTERVAL '24 hours'
+);
+
+CREATE INDEX idx_enrollment_requests_token ON enrollment_requests (polling_token);
+CREATE INDEX idx_enrollment_requests_expires ON enrollment_requests (expires_at);