feat: RBAC, atomic deployments, fleet backups, and licensing (Pro) (#185)

* feat: add RBAC viewer accounts, atomic deployments, and fleet-wide backups (Pro)

Introduces three Pro-tier features:

- RBAC: Multi-user system with admin/viewer roles, user management UI,
  automatic migration from single-admin credentials, viewer restrictions
  across the entire UI (read-only editor, hidden action buttons)

- Atomic Deployments: Pre-deploy file backup to .sencho-backup/, automatic
  rollback on health probe failure, manual rollback button, health probes
  added to stack updates, webhook-triggered deploys use atomic rollback

- Fleet-Wide Backups: Point-in-time snapshots of compose files across all
  nodes (local + remote), stored centrally in SQLite, per-stack restore
  with optional redeploy, graceful handling of offline nodes

* fix(settings): use correct ProGate prop name in UsersSection

* fix(settings): remove unused isPro prop from UsersSection

* fix(auth): fetch user info after login and setup so isAdmin is set correctly

* feat(pricing): revise pricing strategy and enforce variant-based seat limits

Raise Personal Pro from $49/yr to $69/yr with 3 viewer seats (up from 1).
Add $15/mo billing option for Team Pro. Mark lifetime pricing as a
90-day early-adopter offer. Store Lemon Squeezy variant_name on
activation/validation and enforce seat limits server-side per variant.

* feat(licensing): add Lemon Squeezy checkout, webhook, and billing portal integration

Server-side checkout URL generation (POST /api/checkout) with admin email
pre-fill and instance_id custom data. HMAC-SHA256 verified webhook endpoint
(POST /api/webhooks/lemonsqueezy) handling order, subscription, and payment
lifecycle events for automatic license activation. Customer billing portal
link stored from webhook events and exposed via GET /api/billing/portal.
In-app checkout buttons in Settings with manual license key fallback.

* fix(licensing): exempt Lemon Squeezy webhook from auth middleware

The catch-all auth middleware on /api/* was blocking the public webhook
endpoint. Added /webhooks/lemonsqueezy to the exemption list alongside
/auth/* and /webhooks/:id/trigger.

* feat(pricing): update pricing to final live rates

Personal Pro: $7.99/month, $69.99/year, $249 lifetime.
Team Pro: $49.99/month, $499.99/year, $1,499 lifetime.
Added personal_monthly checkout variant across backend, frontend, and website.

* refactor(licensing): remove server-side checkout/webhook for self-hosted model

Sencho is self-hosted — each user runs their own instance, so there is
no central server to receive webhooks or hold the store API key. Replaced
in-app checkout buttons with a "View Pricing" redirect to sencho.io and
kept manual license key activation as the primary flow.

- Delete LemonSqueezyService (checkout, webhook, HMAC verification)
- Remove POST /api/checkout, GET /api/billing/portal, POST /api/webhooks/lemonsqueezy
- Remove raw body parser and auth exemption for webhook route
- Remove all LEMONSQUEEZY_* env vars from .env.example
- Replace checkout buttons in SettingsModal with single "View Pricing" button
- Simplify LicenseContext checkout to open sencho.io pricing page
- Update licensing docs to reflect website-based purchase flow

* chore: normalize em-dashes to hyphens across codebase (linter)

* chore: remove accidentally tracked directories from index

docs/features/global-observability.mdx

@@ -3,7 +3,7 @@ title: Global Observability
 description: A unified, searchable log stream from every container across all your stacks.
 ---
 
-The **Logs** tab aggregates output from all running containers into a single scrollable view. Instead of tailing logs one container at a time, you see everything in one place — with filtering to focus on what matters.
+The **Logs** tab aggregates output from all running containers into a single scrollable view. Instead of tailing logs one container at a time, you see everything in one place - with filtering to focus on what matters.
 
 <Frame>
   <img src="/images/global-observability/global-observability-overview.png" alt="Global Observability view showing real-time log lines from multiple containers" />
@@ -13,11 +13,11 @@ The **Logs** tab aggregates output from all running containers into a single scr
 
 Each line shows:
 
-- **Timestamp** — when the log line was emitted
-- **Stack name** — the Compose stack the container belongs to (colour-coded)
-- **Container name** — the specific container
-- **Level** — `INFO`, `WARN`, or `ERROR` (where detectable)
-- **Message** — the raw log output
+- **Timestamp** - when the log line was emitted
+- **Stack name** - the Compose stack the container belongs to (colour-coded)
+- **Container name** - the specific container
+- **Level** - `INFO`, `WARN`, or `ERROR` (where detectable)
+- **Message** - the raw log output
 
 ## Streaming modes
 
@@ -36,11 +36,11 @@ Use the controls above the log panel to narrow what you see:
 
 | Control | What it does |
 |---------|-------------|
-| **Stack filter** | Multi-select dropdown — show only logs from chosen stacks |
-| **Stream** | `ALL` / `STDOUT` / `STDERR` — filter by output stream |
+| **Stack filter** | Multi-select dropdown - show only logs from chosen stacks |
+| **Stream** | `ALL` / `STDOUT` / `STDERR` - filter by output stream |
 | **Search** | Full-text filter on the message field (case-insensitive) |
 
-Filters combine — you can show only `STDERR` from a specific stack while searching for a keyword.
+Filters combine - you can show only `STDERR` from a specific stack while searching for a keyword.
 
 ## Controls