Add notes API: clinic + author-scoped CRUD

New `note` table (src/db/schema/notes.ts) referencing organization + user,
with org+author scoping so a doctor only sees their own notes within the active
clinic. Adds:

- src/types/note.ts + src/lib/note-validation.ts (zod)
- src/services/notes.ts (CRUD, treats non-uuid ids as not-found)
- src/routes/notes.ts mounted at /api/notes, gated requireAuth → requireOrg
- schema barrel + generated migration drizzle/0001_*.sql (applied on startup
  by the runtime migrator)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/drizzle/meta/_journal.json

@@ -8,6 +8,13 @@
       "when": 1780413912874,
       "tag": "0000_small_sir_ram",
       "breakpoints": true
+    },
+    {
+      "idx": 1,
+      "version": "7",
+      "when": 1780591375930,
+      "tag": "0001_boring_puck",
+      "breakpoints": true
     }
   ]
 }