Add SWPC events support

[samaloney]

PR Description

Add an SWPC Event Fido client to search and download the event files/archives.
Add a parser to parse the files/arhcives into and an astropy QTable/s

AI Assistance Disclosure

AI tools were used for:

• [x ] Code generation (e.g., when writing an implementation or fixing a bug)
• [x ] Test/benchmark generation
• [x ] Documentation (including examples)
• [ ] Research and understanding
• [ ] No AI tools were used

Regardless of AI use, the human contributor remains fully responsible for correctness, design choices, licensing compatibility, and long-term maintainability.

[Copilot]

🟡 Not ready to approve

There are confirmed runtime failure cases (empty archive vstack and empty flare-row handling in the example) plus a few documentation/text issues that should be fixed before merging.

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Pull request overview

Adds first-class support for NOAA SWPC “Edited Solar Events List” data by introducing a SunPy/Fido client for discovery/download and parsers to convert both daily event files and yearly archives into astropy.table.QTable outputs, plus documentation, examples, and tests.

Changes:

• Added SWPCEventsClient (Fido client) to search/fetch daily files and archived yearly tarballs from SWPC FTP.
• Added parsers for single files and yearly archives, plus a dispatcher helper with optional TimeRange filtering.
• Added tests, sample SWPC fixtures, Sphinx API docs entry, a comparison example, and a changelog entry.

File summaries

File	Description
sunkit_instruments/swpc/client.py	New Fido client for SWPC Edited Solar Events List discovery/download.
sunkit_instruments/swpc/parser.py	New parsers for daily files and yearly tar.gz archives, plus dispatcher/filtering.
sunkit_instruments/swpc/init.py	Exposes SWPC client and parsing functions as public API.
sunkit_instruments/swpc/tests/test_client.py	Remote-data tests covering Fido search/fetch behavior.
sunkit_instruments/swpc/tests/test_parser.py	Unit tests for parsing new/old formats, archives, masks, and day rollover.
sunkit_instruments/swpc/tests/init.py	Test package marker.
sunkit_instruments/data/test/swpc_20260710events.txt	New-format fixture for parser tests.
sunkit_instruments/data/test/swpc_19970121events.txt	Old-format fixture for parser tests.
sunkit_instruments/data/test/swpc_19970115events.txt	“No events” fixture for parser tests.
examples/compare_swpc_events_hek.py	Example comparing SWPC XRA events with HEK and GOES XRS flux.
docs/code_ref/swpc.rst	New API reference page for sunkit_instruments.swpc.
docs/code_ref/index.rst	Adds SWPC to the API reference index.
changelog/211.feature.rst	Changelog entry announcing SWPC client/parsers + example.

Review details

• Files reviewed: 12/14 changed files
• Comments generated: 4
• Review effort level: Lite

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