feat(core-shared): add rate-limit type primitives and manifest field

Adds IRateLimit, RateLimitBudget, RateLimitDecision to a new
rate-limit sub-module; adds RateLimited<F> brand and isRateLimited
predicate following the Captured/ConsentChecked pattern; extends
UseCaseManifest with rateLimit?: readonly RateLimitBudget[] so
features can declare rate-limit gates in their manifests.

Exports new types from @repo/core-shared/rate-limit and
@repo/core-shared/conformance. Blocks stories 02, 03, and 04.

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

coverage/summary.json

@@ -1,18 +1,18 @@
 {
-  "generatedAt": "2026-05-19T21:51:40.371Z",
-  "commit": "5151454",
+  "generatedAt": "2026-05-20T08:21:18.294Z",
+  "commit": "a633561",
   "repo": {
     "statements": 97.38,
-    "branches": 92.19,
-    "functions": 97.1,
+    "branches": 92.2,
+    "functions": 97.11,
     "lines": 97.38,
     "counts": {
-      "lf": 5801,
-      "lh": 5649,
-      "brf": 1165,
-      "brh": 1074,
-      "fnf": 345,
-      "fnh": 335
+      "lf": 5807,
+      "lh": 5655,
+      "brf": 1166,
+      "brh": 1075,
+      "fnf": 346,
+      "fnh": 336
     }
   },
   "byPackage": {
@@ -101,17 +101,17 @@
       }
     },
     "@repo/core-shared": {
-      "statements": 98.03,
-      "branches": 95.89,
-      "functions": 92.08,
-      "lines": 98.03,
+      "statements": 98.04,
+      "branches": 95.9,
+      "functions": 92.16,
+      "lines": 98.04,
       "counts": {
-        "lf": 1067,
-        "lh": 1046,
-        "brf": 316,
-        "brh": 303,
-        "fnf": 101,
-        "fnh": 93
+        "lf": 1073,
+        "lh": 1052,
+        "brf": 317,
+        "brh": 304,
+        "fnf": 102,
+        "fnh": 94
       }
     },
     "@repo/core-ui": {