feat: public platform, admin console, templates, landing docs

Projects become publicly browsable after admin approval; management and
secret-adjacent reads (logs, variables, exec, connection URLs) require
owner/member/admin auth, and platform controls sit behind RequireAdmin.

- Backend: OptionalAuth middleware, read/authed/admin route groups,
  projects.is_approved + service_templates.owner_id migration,
  visibility-aware sqlc queries, admin overview/users/approval endpoints,
  EnsureAdminAccount bootstrap (ADMIN_* env), 30 seeded templates with
  owner CRUD, managed-database connection URLs gated owner+admin, fix
  DB.Stats() infinite recursion.
- Frontend: expandable persisted sidebar + clickable user menu, public
  landing page with searchable docs browser (GitHub sync, bundled
  snapshot + localStorage fallback), DocsBrowser shared with /docs,
  template create/edit/JSON-upload for owned templates, database create
  dialog, admin console (stats, approvals, project edit/delete, user
  admin toggles), HA/Security/Usage polish with dead CSS tokens mapped
  to real theme vars, anonymous-safe gating on every mutation control.
- Tests: safe window.localStorage access fixes happy-dom crashes in
  PlatformShell and canvas storage.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/database/sqlcdb/models.go

@@ -154,6 +154,7 @@ type Project struct {
 	Name        string         `json:"name"`
 	Description sql.NullString `json:"description"`
 	OwnerID     uuid.UUID      `json:"owner_id"`
+	IsApproved  bool           `json:"is_approved"`
 	CreatedAt   sql.NullTime   `json:"created_at"`
 	UpdatedAt   sql.NullTime   `json:"updated_at"`
 }
@@ -205,6 +206,7 @@ type ServiceTemplate struct {
 	Config      json.RawMessage       `json:"config"`
 	Variables   pqtype.NullRawMessage `json:"variables"`
 	IsOfficial  sql.NullBool          `json:"is_official"`
+	OwnerID     uuid.NullUUID         `json:"owner_id"`
 	CreatedAt   sql.NullTime          `json:"created_at"`
 	UpdatedAt   sql.NullTime          `json:"updated_at"`
 }