Add SvelteKit frontend with Tailwind CSS (Phase 4)

Build a modern, calm web UI using SvelteKit 5 + Tailwind CSS v4.

Pages:
- Setup wizard (first-run admin account creation)
- Login with JWT token management and auto-refresh
- Dashboard with stats cards and recent events timeline
- Servers: add/delete Immich server connections with validation
- Trackers: create album trackers with album picker, event type
  selection, target assignment, and scan interval config
- Templates: Jinja2 message template editor with live preview
- Targets: Telegram and webhook notification targets with test
- Users: admin-only user management (create/delete)

Architecture:
- Reactive auth state with Svelte 5 runes
- API client with JWT auth, auto-refresh on 401
- Static adapter builds to 153KB for embedding in FastAPI
- Vite proxy config for dev server -> backend API
- Sidebar layout with navigation and user info

Also adds Rule 2 to primary plan: perform detailed code review
after completing each phase.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plans/primary-plan.md

@@ -172,7 +172,9 @@ async def _execute_telegram_notification(self, ...):
 
 ## Phases
 
-> **Rule**: Before starting work on any phase, create a detailed trackable subplan at `plans/phase-N-<name>.md` with granular tasks, specific files to create/modify, and acceptance criteria. Do not begin implementation until the subplan is reviewed.
+> **Rule 1**: Before starting work on any phase, create a detailed trackable subplan at `plans/phase-N-<name>.md` with granular tasks, specific files to create/modify, and acceptance criteria. Do not begin implementation until the subplan is reviewed.
+>
+> **Rule 2**: After completing each phase, perform a detailed code review of all changes. Use the `code-reviewer` agent to check for bugs, logic errors, security vulnerabilities, code quality issues, and adherence to project conventions. Document review findings in the phase subplan under a "## Review" section and fix any issues before committing.
 
 ### Phase 1: Extract Core Library `[x]`
 - Extract models, Immich client, change detection, Telegram client, cache into `packages/core/`
@@ -192,7 +194,7 @@ async def _execute_telegram_notification(self, ...):
 - Jinja2 template engine with variable system matching blueprint
 - **Subplan**: `plans/phase-3-server-backend.md`
 
-### Phase 4: Build Frontend `[ ]`
+### Phase 4: Build Frontend `[x]`
 - SvelteKit app with all pages (setup, dashboard, trackers, templates, targets, users)
 - Template editor with live preview
 - Album picker connected to Immich API