Add Projects, Milestones, RAG auto-inject, push notifications, PWA, tag normalisation

## Projects & Milestones (Phases A + G)
- New models: Project, Milestone (Project → Milestone → Task hierarchy)
- notes table: project_id + milestone_id FKs; parent_id FK constraint activated
- Migrations: 0017 (projects), 0018 (push_subscriptions), 0019 (events), 0020 (milestones)
- Services: projects.py, milestones.py (CRUD + progress tracking)
- Routes: /api/projects + /api/projects/<id>/milestones
- LLM tools: create/list/get/update project; create/list milestone; project + milestone + parent_task params on note/task tools
- Frontend: ProjectListView (stacked milestone bars), ProjectView (milestone-grouped kanban), ProjectSelector, MilestoneSelector, NoteEditorView + TaskEditorView updated

## RAG Auto-injection (Phase B)
- Notes ≥0.60 cosine similarity auto-injected into system prompt (max 3, 800 chars each)
- excluded_note_ids param; ChatView "Auto-included" sidebar section

## Summarisation improvements (Phase C)
- Threshold 20→30, keep-recent 6→8, max_tokens 200→400
- Two-pass summarisation for histories >50 messages

## Browser push notifications (Phase E)
- PushSubscription model + migration; pywebpush dependency
- /api/push routes; VAPID config; fire-and-forget on generation complete
- Frontend: sw.js, push store, Settings toggle

## PWA manifest (Phase F)
- manifest.json, Apple meta tags, service worker registration in main.ts

## Tag normalisation
- All tags lowercased + deduplicated at backend (create_note/update_note) and frontend (TagInput sanitize)
- Note/Task types gain project_id + milestone_id fields; store signatures updated

## CalDAV
- Radicale embedded server reverted; back to user-configured external CalDAV

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

frontend/src/components/ProjectSelector.vue

@@ -0,0 +1,67 @@
+<script setup lang="ts">
+import { ref, onMounted } from "vue";
+import { apiGet } from "@/api/client";
+
+interface Project {
+  id: number;
+  title: string;
+  status: string;
+}
+
+defineProps<{
+  modelValue: number | null;
+}>();
+
+const emit = defineEmits<{
+  (e: "update:modelValue", value: number | null): void;
+}>();
+
+const projects = ref<Project[]>([]);
+let cacheExpiry = 0;
+
+async function loadProjects() {
+  const now = Date.now();
+  if (projects.value.length > 0 && now < cacheExpiry) return;
+  try {
+    const data = await apiGet<{ projects: Project[] }>("/api/projects?status=active");
+    projects.value = data.projects;
+    cacheExpiry = now + 60_000; // 60 second cache
+  } catch {
+    // Silently fail — selector will just be empty
+  }
+}
+
+onMounted(loadProjects);
+
+function onChange(e: Event) {
+  const value = (e.target as HTMLSelectElement).value;
+  emit("update:modelValue", value ? Number(value) : null);
+}
+</script>
+
+<template>
+  <select class="project-selector" :value="modelValue ?? ''" @change="onChange">
+    <option value="">No project</option>
+    <option v-for="project in projects" :key="project.id" :value="project.id">
+      {{ project.title }}
+    </option>
+  </select>
+</template>
+
+<style scoped>
+.project-selector {
+  padding: 0.4rem 0.5rem;
+  border: 1px solid var(--color-input-border);
+  border-radius: var(--radius-sm);
+  background: var(--color-bg-card);
+  color: var(--color-text);
+  font-size: 0.9rem;
+  font-family: inherit;
+  width: 100%;
+  box-sizing: border-box;
+}
+.project-selector:focus {
+  outline: none;
+  border-color: var(--color-primary);
+}
+</style>