hub v0.3.1: Config diff display + pull config

Replace broken SHA256 hash comparison with value-based YAML comparison.
Add "Show Diff" button showing per-key differences in a color-coded table.
Add "Pull Config" to import controller's current config into the Hub.
New endpoints: GET /customers/{id}/config-diff, POST /customers/{id}/pull-config.

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

hub/README.md

@@ -4,7 +4,7 @@
 
 A lightweight Go service that receives periodic reports and structured events from felhom-controller instances, stores them in SQLite, and provides a web dashboard for fleet monitoring. Also serves as the infrastructure backup store for disaster recovery, event-based dead man's switch monitoring, and notification dispatch.
 
-**Current version: v0.3.0**
+**Current version: v0.3.1**
 
 ---
 
@@ -139,6 +139,8 @@ Protected by bcrypt password + session cookie (7-day expiry).
 |--------|-------------|
 | **Block/Unblock** | Toggle blocked status — blocked customers are hidden from dashboard and notifications are suppressed, but reports are still accepted and stored |
 | **Push Config** | Generate YAML from Hub config and POST it to the controller's `/api/config/apply` endpoint (requires controller URL from reports) |
+| **Pull Config** | Import controller's current config into Hub — fetches live YAML via `GET /api/config`, extracts identity and override fields, updates Hub's stored config |
+| **Show Diff** | Compare Hub-generated config with controller's live config — shows per-key differences in a color-coded table (value-based comparison, ignores key ordering and volatile fields) |
 | **Create Config** | Auto-create a managed config from a manual customer's report data, then redirect to edit form |
 | **Trigger Update** | Instruct controller to self-update to the latest version |
 | **Delete** | Remove customer config (customer reappears as manual if reports continue) |