feat: add 'caselaw' (פסיקה) kind alongside חוק/תקנות/חוזרים

Court rulings get their own kind so users can filter search results
to "פסיקה" specifically and upload case-law PDFs from the ניהול tab.
PHP validators in Controller + Service accept the new kind; the search
dropdown and upload kind dropdown gain a "פסיקה" option; kindHe in
index.js maps caselaw → "פסיקה" so jobs list, search results, and
browse view all label it consistently.

Backend: depends on shira-hermes commit 16eeeff (kind validators +
chunker fallback) and migration 003_caselaw_kind.sql (already applied
on dev — alters CHECK constraints on kb_source.kind and
kb_ingest_job.kind to include 'caselaw').

Refs Task Master #18

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

.taskmaster/state.json

@@ -2,5 +2,5 @@
   "currentTag": "master",
   "lastSwitched": "2026-04-24T15:47:33.139Z",
   "branchTagMapping": {},
-  "migrationNoticeShown": false
+  "migrationNoticeShown": true
 }