Add per-folder CLAUDE.md for key packages

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

e2e/CLAUDE.md

@@ -0,0 +1,48 @@
+# e2e
+
+End-to-end tests against a running `bin/probod` instance.
+
+## Prerequisites
+
+Build the binary first: `make build` (or `SKIP_APPS=1 make build` for backend-only).
+
+## Running
+
+```
+make test-e2e
+```
+
+## Test setup
+
+`testutil.Setup()` starts `bin/probod` as a subprocess (once per test run) and waits for the GraphQL endpoint to be healthy.
+
+## Client
+
+```go
+c := testutil.NewClient(t, testutil.RoleOwner)
+```
+
+The client carries organization/tenant context and provides:
+- `c.Execute(query, variables, &result)` — GraphQL queries
+- `c.ExecuteConnect(query, variables, &result)` — Connect API queries
+- `c.GetOrganizationID()` — current org
+
+## Factory pattern
+
+Test data created via `factory.Create*` functions:
+
+```go
+vendorID := factory.CreateVendor(c, factory.Attrs{"name": "Acme"})
+userID := factory.CreateUser(c)
+```
+
+- `factory.SafeName(prefix)` — random unique names
+- `factory.SafeEmail()` — random unique emails
+- `factory.Attrs` map for overriding defaults
+
+## Test structure
+
+- Always `t.Parallel()` at the test function level
+- Inline GraphQL queries as string constants
+- Typed result structs per query
+- `require.NoError` for mutation/query errors, `assert.Equal` for value checks