feat: implement LiquidJS template rendering integration

Integrates LiquidJS as the template engine for CAS node rendering with
custom {% render %} tag supporting recursive rendering with resolution
decay. Templates are discovered via variables under
@ucas/template/text/<type-hash>. When ucas render <hash> is invoked,
the system queries for a registered template; if found, uses LiquidJS;
otherwise falls back to Phase 3's default YAML renderer.

Key features:
- Custom {% render %} tag with recursive CAS node rendering
- Decay priority chain: template decay > CLI --decay > default 0.5
- Context variables: resolution, epsilon, hash, payload, type, timestamp
- Graceful fallback: No template → YAML rendering (Phase 3)
- Zero breaking changes: All Phase 3 tests still pass
- Template discovery via @ucas/template/text/<type-hash> variables

Implementation:
- New file: packages/json-cas/src/liquid-render.ts — LiquidJS integration
- Modified: packages/json-cas/src/render.ts — Template lookup + YAML fallback
- New file: packages/json-cas/src/liquid-render.test.ts — 32 comprehensive tests
- Dependency: liquidjs npm package
- CLI: No changes needed (transparent integration)

All tests pass (336 tests), build succeeds, lint checks pass.

Closes #40

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

bun.lock

@@ -30,6 +30,7 @@
       "dependencies": {
         "ajv": "^8.20.0",
         "cborg": "^4.2.3",
+        "liquidjs": "^10.27.0",
         "xxhash-wasm": "^1.1.0",
       },
     },
@@ -141,6 +142,8 @@
 
     "chardet": ["chardet@2.1.1", "", {}, "sha512-PsezH1rqdV9VvyNhxxOW32/d75r01NY7TQCmOqomRo15ZSOKbpTFVsfjghxo6JloQUCGnH4k1LGu0R4yCLlWQQ=="],
 
+    "commander": ["commander@10.0.1", "", {}, "sha512-y4Mg2tXshplEbSGzx7amzPwKKOCGuoSRP/CjEdwwk0FOGlUbq6lKuoyDZTNZkmxHdJtp54hdfY/JUrdL7Xfdug=="],
+
     "cross-spawn": ["cross-spawn@7.0.6", "", { "dependencies": { "path-key": "^3.1.0", "shebang-command": "^2.0.0", "which": "^2.0.1" } }, "sha512-uV2QOWP2nWzsy2aMp8aRibhi9dlzF5Hgh5SHaB9OiTGEyDTiJJyx0uy51QXdyWbtAHNua4XJzUKca3OzKUd3vA=="],
 
     "dataloader": ["dataloader@1.4.0", "", {}, "sha512-68s5jYdlvasItOJnCuI2Q9s4q98g0pCyL3HrcKJu8KNugUl8ahgmZYg38ysLTgQjjXX3H8CJLkAvWrclWfcalw=="],
@@ -203,6 +206,8 @@
 
     "layerr": ["layerr@3.0.0", "", {}, "sha512-tv754Ki2dXpPVApOrjTyRo4/QegVb9eVFq4mjqp4+NM5NaX7syQvN5BBNfV/ZpAHCEHV24XdUVrBAoka4jt3pA=="],
 
+    "liquidjs": ["liquidjs@10.27.0", "", { "dependencies": { "commander": "^10.0.0" }, "bin": { "liquidjs": "bin/liquid.js", "liquid": "bin/liquid.js" } }, "sha512-tw/OA59K7aIBlMKIrKlumr37fiZUheShVHXY8cVctWisgY1p9mc5hreOvlreoS0wTiwlWk14Ya7305c2a/Cg5w=="],
+
     "locate-path": ["locate-path@5.0.0", "", { "dependencies": { "p-locate": "^4.1.0" } }, "sha512-t7hw9pI+WvuwNJXwk5zVHpyhIqzg2qTlklJOf0mVxGSbe3Fp2VieZcduNYjaLDoy6p9uGpQEGWG87WpMKlNq8g=="],
 
     "lodash.startcase": ["lodash.startcase@4.4.0", "", {}, "sha512-+WKqsK294HMSc2jEbNgpHpd0JfIBhp7rEV4aqXWqFr6AlXov+SlcgB1Fv01y2kGe3Gc8nMW7VA0SrGuSkRfIEg=="],