implement Plunk email driver with comprehensive tests

- Add plunkEmail driver following IEmailDriver interface
- Support single and multiple recipients (up to 5 max per Plunk API)
- Handle both string and { text, html } body formats
- Include sender customization (from, name, reply)
- Add recipient validation and error handling
- Create comprehensive unit tests with 6 test cases
- Export plunkEmail from core drivers index
- Update task list with implementation progress

tasks/tasks-plunk-email-driver.md

@@ -26,41 +26,41 @@ Update the file after completing each sub-task, not just after completing an ent
 
 ## Tasks
 
-- [ ] 0.0 Create feature branch
-  - [ ] 0.1 Verify current branch (already on `claude/add-loops-email-driver-011CUxMpVqe8AT22gN2k5ZVm`)
+- [x] 0.0 Create feature branch
+  - [x] 0.1 Verify current branch (already on `claude/add-loops-email-driver-011CUxMpVqe8AT22gN2k5ZVm`)
 
-- [ ] 1.0 Implement Plunk email driver
-  - [ ] 1.1 Read `resend.ts` file to understand the factory pattern and implementation structure
-  - [ ] 1.2 Create `/home/user/bknd/app/src/core/drivers/email/plunk.ts` file
-  - [ ] 1.3 Define `PlunkEmailOptions` type with `apiKey`, `host?`, and `from?` fields
-  - [ ] 1.4 Define `PlunkEmailSendOptions` type with `to?`, `subscribed?`, `name?`, `from?`, `reply?`, and `headers?` fields
-  - [ ] 1.5 Define `PlunkEmailResponse` type matching Plunk's API response structure (`success`, `emails`, `timestamp`)
-  - [ ] 1.6 Implement `plunkEmail()` factory function that accepts config and returns `IEmailDriver` instance
-  - [ ] 1.7 Implement `send()` method with proper body handling (string vs `{ text, html }` object)
-  - [ ] 1.8 Add recipient validation to ensure max 5 recipients when `options.to` is an array
-  - [ ] 1.9 Add HTTP request implementation using `fetch()` with proper headers (Authorization, Content-Type)
-  - [ ] 1.10 Add error handling for failed API responses (check `res.ok` and throw with error text)
-  - [ ] 1.11 Implement proper payload construction with `to`, `subject`, `body`, and optional fields
+- [x] 1.0 Implement Plunk email driver
+  - [x] 1.1 Read `resend.ts` file to understand the factory pattern and implementation structure
+  - [x] 1.2 Create `/home/user/bknd/app/src/core/drivers/email/plunk.ts` file
+  - [x] 1.3 Define `PlunkEmailOptions` type with `apiKey`, `host?`, and `from?` fields
+  - [x] 1.4 Define `PlunkEmailSendOptions` type with `to?`, `subscribed?`, `name?`, `from?`, `reply?`, and `headers?` fields
+  - [x] 1.5 Define `PlunkEmailResponse` type matching Plunk's API response structure (`success`, `emails`, `timestamp`)
+  - [x] 1.6 Implement `plunkEmail()` factory function that accepts config and returns `IEmailDriver` instance
+  - [x] 1.7 Implement `send()` method with proper body handling (string vs `{ text, html }` object)
+  - [x] 1.8 Add recipient validation to ensure max 5 recipients when `options.to` is an array
+  - [x] 1.9 Add HTTP request implementation using `fetch()` with proper headers (Authorization, Content-Type)
+  - [x] 1.10 Add error handling for failed API responses (check `res.ok` and throw with error text)
+  - [x] 1.11 Implement proper payload construction with `to`, `subject`, `body`, and optional fields
 
-- [ ] 2.0 Create unit tests for Plunk driver
-  - [ ] 2.1 Read `resend.spec.ts` to understand test pattern and structure
-  - [ ] 2.2 Create `/home/user/bknd/app/src/core/drivers/email/plunk.spec.ts` file
-  - [ ] 2.3 Set up test structure with `describe.skipIf(ALL_TESTS)` wrapper
-  - [ ] 2.4 Write test: "should throw on failed" - test with invalid API key expecting error
-  - [ ] 2.5 Write test: "should send an email" - test successful email send (requires `PLUNK_API_KEY` env var)
-  - [ ] 2.6 Write test: "should send HTML email" - test with HTML string body
-  - [ ] 2.7 Write test: "should send with text and html" - test with `{ text, html }` body object
-  - [ ] 2.8 Write test: "should send to multiple recipients" - test with array of recipients in options
+- [x] 2.0 Create unit tests for Plunk driver
+  - [x] 2.1 Read `resend.spec.ts` to understand test pattern and structure
+  - [x] 2.2 Create `/home/user/bknd/app/src/core/drivers/email/plunk.spec.ts` file
+  - [x] 2.3 Set up test structure with `describe.skipIf(ALL_TESTS)` wrapper
+  - [x] 2.4 Write test: "should throw on failed" - test with invalid API key expecting error
+  - [x] 2.5 Write test: "should send an email" - test successful email send (requires `PLUNK_API_KEY` env var)
+  - [x] 2.6 Write test: "should send HTML email" - test with HTML string body
+  - [x] 2.7 Write test: "should send with text and html" - test with `{ text, html }` body object
+  - [x] 2.8 Write test: "should send to multiple recipients" - test with array of recipients in options
 
-- [ ] 3.0 Update driver exports
-  - [ ] 3.1 Read current `/home/user/bknd/app/src/core/drivers/index.ts` file
-  - [ ] 3.2 Add `export { plunkEmail } from "./email/plunk";` to `/home/user/bknd/app/src/core/drivers/index.ts`
+- [x] 3.0 Update driver exports
+  - [x] 3.1 Read current `/home/user/bknd/app/src/core/drivers/index.ts` file
+  - [x] 3.2 Add `export { plunkEmail } from "./email/plunk";` to `/home/user/bknd/app/src/core/drivers/index.ts`
 
-- [ ] 4.0 Verify implementation and run tests
-  - [ ] 4.1 Run Plunk driver tests with `bun test app/src/core/drivers/email/plunk.spec.ts`
-  - [ ] 4.2 Verify all tests pass (or only skip if `ALL_TESTS` is true and no `PLUNK_API_KEY`)
-  - [ ] 4.3 Review code for consistency with existing drivers (resend.ts pattern)
-  - [ ] 4.4 Verify TypeScript types are correctly defined and exported
+- [x] 4.0 Verify implementation and run tests
+  - [x] 4.1 Run Plunk driver tests with `bun test app/src/core/drivers/email/plunk.spec.ts`
+  - [x] 4.2 Verify all tests pass (or only skip if `ALL_TESTS` is true and no `PLUNK_API_KEY`)
+  - [x] 4.3 Review code for consistency with existing drivers (resend.ts pattern)
+  - [x] 4.4 Verify TypeScript types are correctly defined and exported
 
 - [ ] 5.0 Commit and push changes
   - [ ] 5.1 Stage all changed files (`plunk.ts`, `plunk.spec.ts`, `index.ts`)