feat: add per-source mail import trigger

docs/development/roadmap.md

@@ -27,6 +27,7 @@ Recently improved:
 - Parsed upload, Gmail, and IMAP reports are now persisted to `dmarc_reports` and `report_records`.
 - Report/domain API reads can hydrate the dashboard projection from persisted data after restart.
 - Mail source import history is visible in the Mail Sources UI.
+- Individual mail sources can be manually imported from the Mail Sources UI.
 - The current Alpine-based UI is allowed by CSP and renders dynamic tables in real browsers.
 
 Implementation note:

docs/milestones.md

@@ -62,6 +62,7 @@ Recently delivered:
 - Mail source imports now persist sanitized import-history records for manual and scheduled polls.
 - Uploaded, Gmail-imported, and IMAP-imported reports are now persisted to report/record tables and can be reloaded into report/domain views.
 - Mail source import history is now visible from the Mail Sources UI.
+- A single mail source can be manually imported from the Mail Sources UI, with the result recorded in import history.
 - The current Alpine-based UI can run under the configured CSP, so dynamic tables render in real browsers.
 
 Next tasks:

docs/todo.md

@@ -91,6 +91,7 @@ This file tracks the specific implementation tasks for each milestone of the DMA
 - [x] Persist sanitized import errors for API/UI review
 - [x] Count duplicate skips separately from parse failures
 - [x] Show recent import history in the Mail Sources UI
+- [x] Add manual import trigger per mail source
 - [ ] Add retry/backfill controls per mail source
 
 ## Milestone 3: Database Integration