feat(api): CUST-WP-0018 — API hardening & code quality

T01: Fix datetime.utcnow() → datetime.now(tz=timezone.utc) in MCP server
T02: Wrap _get/_post/_patch/_delete with try/except; return error dicts
T03: Log warnings when write_log skips missing project path
T04: Add priority + due_date_before filters to GET /tasks/
T05: Add owner + slug filters to GET /workstreams/
T06: Add offset param to GET /progress/ for proper pagination
T07: Low-severity bundle:
  - CORS origins from CORS_ORIGINS env var (TD-017)
  - seed.py upsert domains+topics on re-run (TD-011)
  - normalise filter bar CSS → filter-text-input everywhere (TD-016)
  - add 30.5 avg-days-per-month comment in decisions.md (TD-019)
  - TD-009, TD-018 already resolved by existing code

Closes CUST-WP-0018.

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

dashboard/src/workstreams.md

@@ -232,7 +232,7 @@ const _filtersForm = Inputs.form(
   {
     template: ({domain, status, owner}) => html`<div class="filter-bar">
       ${domain}${status}
-      <div class="filter-owner">${owner}</div>
+      <div class="filter-text-input">${owner}</div>
     </div>`,
   }
 );