feat: Add task-scoped kwargs key/value filtering to task search

[li-ashim]

Problem

Task list search was limited to task name/id or status, making it hard to find tasks by business identifiers stored in kwargs (for example, entity_id=A-100).

Solution

This PR adds task-scoped kwargs filtering with dynamic key discovery:

• extend task search query with task_name, arg_key, arg_value
• add dynamic argument-key options endpoint for selected task name
• apply key/value filtering in repository for both Postgres and SQLite
• preserve filter state through HTMX updates, sorting links, and infinite scroll

Implementation details

• API/router:
  • normalize and trim all new filters
  • add GET /filters/arg-keys for key options partial rendering
• Domain:
  • extend AbstractTaskRepository with find_task_names and find_argument_keys
• Infrastructure:
  • implement task-name and argument-key discovery
  • implement DB-specific kwargs filtering:
    • Postgres JSONB access
    • SQLite json_extract
• Templates:
  • add task-name, arg-key, arg-value controls in home.html
  • add partial/arg_key_options.html
  • keep new filters in list partial pagination/sort flow

Tests

Added and updated tests covering:

• integration (Postgres): task name filtering, kwargs key/value filtering, task-scoped key extraction
• unit (router): filter normalization and HTMX behavior
• unit (SQLite): kwargs filtering and task-scoped key extraction
• edge case: arg filtering ignored when task name is not selected