docs/PR_PLUGIN_AUTHORING.md

PR Title: docs: Add plugin authoring doc, examples, and tests

Summary:
- Add `docs/plugin_authoring.md` describing the strict `ResultModel`-based plugin adapter pattern, `ColumnSpec` usage, `selection_fn`, and `TablePluginMixin` for HTML table scraping.
- Link the new doc from `docs/result_table.md`.
- Add plugin-author example coverage to validate the example plugin integration with the registry.

Why:
- Provide a short, focused Quick Start to help contributors author plugins that integrate with the strict ResultTable API.

Testing:
- New tests pass locally (plugin-related subset).

Notes:
- The change is documentation-first and non-functional, with tests ensuring examples remain valid.
update 2026-05-16 15:26:08 -07:00			`PR Title: docs: Add plugin authoring doc, examples, and tests`
refactor(download): remove ProviderCore/download.py, move sanitize_filename to SYS.utils, replace callers to use API.HTTP.HTTPClient 2026-01-06 01:38:59 -08:00
			`Summary:`
cleanup and rename provider to plugin 2026-05-21 16:19:17 -07:00			- Add `docs/plugin_authoring.md` describing the strict `ResultModel`-based plugin adapter pattern, `ColumnSpec` usage, `selection_fn`, and `TablePluginMixin` for HTML table scraping.
update 2026-05-16 15:26:08 -07:00			- Link the new doc from `docs/result_table.md`.
cleanup and rename provider to plugin 2026-05-21 16:19:17 -07:00			`- Add plugin-author example coverage to validate the example plugin integration with the registry.`
refactor(download): remove ProviderCore/download.py, move sanitize_filename to SYS.utils, replace callers to use API.HTTP.HTTPClient 2026-01-06 01:38:59 -08:00
			`Why:`
update 2026-05-16 15:26:08 -07:00			`- Provide a short, focused Quick Start to help contributors author plugins that integrate with the strict ResultTable API.`
refactor(download): remove ProviderCore/download.py, move sanitize_filename to SYS.utils, replace callers to use API.HTTP.HTTPClient 2026-01-06 01:38:59 -08:00
			`Testing:`
update 2026-05-16 15:26:08 -07:00			`- New tests pass locally (plugin-related subset).`
refactor(download): remove ProviderCore/download.py, move sanitize_filename to SYS.utils, replace callers to use API.HTTP.HTTPClient 2026-01-06 01:38:59 -08:00
			`Notes:`
			`- The change is documentation-first and non-functional, with tests ensuring examples remain valid.`