feat(snippets): named reusable artifacts with scope mirroring memories

Snippets are exact-name-keyed templates (PR formats, checklists, style
rules) — prescriptive artifacts the user wants applied consistently.
Distinct from memories, which are searched descriptive prose.

- Migration 0002 adds scope/project_id/deleted_at to snippets, partial
  unique indexes per scope, and a scope/project CHECK constraint
  mirroring memories_scope_project_chk.
- New @shared-memory/schemas: SnippetName/Put/Get/List/Delete inputs
  with shared scope-project refinement.
- lib/snippets.ts: get/put/list/softDelete helpers used by both the
  Web Server Actions and the MCP tool handlers.
- Four new MCP tools (snippet.put/get/list/delete) with directive
  descriptions contrasting against memory.* (exact-name lookup vs
  search; templates vs facts).
- /snippets pages: list, new, [name] with edit + delete and a
  scope-picker when a name lives in multiple scopes.
- Nav: Snippets link between Memories and Projects.

Design note: when a name exists in both user and project scope,
snippet.get without an explicit scope prefers project (if project key
given) then falls back to user. The detail page shows a picker when
the name is ambiguous and no scope query param was supplied.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/app/(authed)/snippets/new/page.tsx

@@ -0,0 +1,137 @@
+import Link from "next/link";
+import { desc, eq } from "drizzle-orm";
+import { auth } from "@/auth";
+import { db } from "@/lib/db/client";
+import { projects } from "@/lib/db/schema";
+import { createSnippetAction } from "@/lib/snippet-actions";
+import { Container, PageHeader } from "@/app/_components/ui/container";
+import { Card, CardBody } from "@/app/_components/ui/card";
+import { Input, Textarea, Label } from "@/app/_components/ui/input";
+import { Button } from "@/app/_components/ui/button";
+
+export const dynamic = "force-dynamic";
+
+export default async function NewSnippetPage({
+  searchParams,
+}: {
+  searchParams: Promise<{ scope?: string; project?: string; name?: string }>;
+}) {
+  const session = await auth();
+  const userId = session!.user.id;
+  const params = await searchParams;
+  const initialScope = params.scope === "project" ? "project" : "user";
+  const initialProject = params.project ?? "";
+  const initialName = params.name ?? "";
+
+  const projectList = await db
+    .select({ key: projects.key, displayName: projects.displayName })
+    .from(projects)
+    .where(eq(projects.userId, userId))
+    .orderBy(desc(projects.updatedAt))
+    .limit(50);
+
+  return (
+    <Container className="pt-6 max-w-2xl">
+      <PageHeader
+        title="New snippet"
+        description="Name it something stable — that name is the lookup key from now on."
+      />
+
+      <Card>
+        <CardBody>
+          <form action={createSnippetAction} className="space-y-4">
+            <div>
+              <Label htmlFor="name" hint="alphanumerics + ._-/">
+                Name
+              </Label>
+              <Input
+                id="name"
+                name="name"
+                required
+                defaultValue={initialName}
+                placeholder="pr-description-format"
+                className="mt-1 font-mono"
+              />
+            </div>
+
+            <div>
+              <Label htmlFor="scope">Scope</Label>
+              <select
+                id="scope"
+                name="scope"
+                defaultValue={initialScope}
+                className="mt-1 h-9 px-2 rounded-md bg-surface-1 border border-border text-fg text-sm w-full"
+              >
+                <option value="user">User — applies everywhere (default)</option>
+                <option value="project">Project — tied to a specific repo</option>
+              </select>
+            </div>
+
+            <div>
+              <Label htmlFor="project" hint="Required for project scope">
+                Project key
+              </Label>
+              <Input
+                id="project"
+                name="project"
+                defaultValue={initialProject}
+                placeholder="repo name, slug, or any stable string"
+                list="project-list"
+                className="mt-1"
+              />
+              {projectList.length > 0 ? (
+                <datalist id="project-list">
+                  {projectList.map((p) => (
+                    <option key={p.key} value={p.key}>
+                      {p.displayName ?? p.key}
+                    </option>
+                  ))}
+                </datalist>
+              ) : null}
+            </div>
+
+            <div>
+              <Label htmlFor="description" hint="Optional">
+                Description
+              </Label>
+              <Input
+                id="description"
+                name="description"
+                placeholder="When should this template be used?"
+                className="mt-1"
+              />
+            </div>
+
+            <div>
+              <Label htmlFor="body">Body</Label>
+              <Textarea
+                id="body"
+                name="body"
+                required
+                rows={14}
+                placeholder="The full template, format, or checklist…"
+                className="mt-1"
+              />
+            </div>
+
+            <div>
+              <Label htmlFor="tags" hint="comma- or space-separated">
+                Tags
+              </Label>
+              <Input id="tags" name="tags" placeholder="format, review, …" className="mt-1" />
+            </div>
+
+            <div className="flex justify-end gap-2 pt-2">
+              <Link href="/snippets" className="no-underline">
+                <Button type="button" variant="secondary">
+                  Cancel
+                </Button>
+              </Link>
+              <Button type="submit">Save snippet</Button>
+            </div>
+          </form>
+        </CardBody>
+      </Card>
+    </Container>
+  );
+}