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/overview.mdx

@@ -13,7 +13,7 @@ Full in-browser code editor for your Compose and environment files. Toggle edit
 
 ## Multi-node support
 
-Add remote Sencho instances as nodes. All dashboard operations — stack management, logs, stats — work identically whether you're targeting your local machine or a server on the other side of the world. Uses a transparent HTTP proxy model; no SSH or shared Docker sockets required. [Learn more →](/features/multi-node)
+Add remote Sencho instances as nodes. All dashboard operations - stack management, logs, stats - work identically whether you're targeting your local machine or a server on the other side of the world. Uses a transparent HTTP proxy model; no SSH or shared Docker sockets required. [Learn more →](/features/multi-node)
 
 ## Fleet View
 
@@ -21,7 +21,7 @@ Monitor your entire infrastructure from a single screen. The fleet dashboard sho
 
 ## RBAC & user management
 
-Create viewer accounts with read-only access to dashboards, logs, and file contents — while keeping deploy and edit permissions locked to admins. Sencho Pro supports two roles: Admin (full access) and Viewer (read-only). [Learn more →](/features/rbac)
+Create viewer accounts with read-only access to dashboards, logs, and file contents - while keeping deploy and edit permissions locked to admins. Sencho Pro supports two roles: Admin (full access) and Viewer (read-only). [Learn more →](/features/rbac)
 
 ## Atomic deployments
 
@@ -29,7 +29,7 @@ Pro users get automatic backup and rollback on every deployment. Before applying
 
 ## Fleet-wide backups
 
-Create point-in-time snapshots of every compose file and environment file across all nodes. Snapshots are stored centrally and can be browsed by node and stack. Restore individual stacks from any snapshot with optional one-click redeploy — even to remote nodes. Offline nodes are gracefully skipped with visible warnings. [Learn more →](/features/fleet-backups)
+Create point-in-time snapshots of every compose file and environment file across all nodes. Snapshots are stored centrally and can be browsed by node and stack. Restore individual stacks from any snapshot with optional one-click redeploy - even to remote nodes. Offline nodes are gracefully skipped with visible warnings. [Learn more →](/features/fleet-backups)
 
 ## Real-time logs & stats
 
@@ -57,11 +57,11 @@ Browse 190+ pre-configured application templates. Filter by category (Media, Aut
 
 ## Host console
 
-Open an interactive terminal on the host OS directly in the browser — full xterm.js emulation with color support. No SSH client required.
+Open an interactive terminal on the host OS directly in the browser - full xterm.js emulation with color support. No SSH client required.
 
 ## Webhooks
 
-Trigger stack actions from external CI/CD pipelines via HTTP webhooks. Create a webhook targeting a specific stack and action, then call it from GitHub Actions, GitLab CI, or any system that can send an HTTP POST. Requests are authenticated with HMAC-SHA256 signatures — no session cookies required. [Learn more →](/features/webhooks)
+Trigger stack actions from external CI/CD pipelines via HTTP webhooks. Create a webhook targeting a specific stack and action, then call it from GitHub Actions, GitLab CI, or any system that can send an HTTP POST. Requests are authenticated with HMAC-SHA256 signatures - no session cookies required. [Learn more →](/features/webhooks)
 
 ## Alerts & notifications