go: better fetch

[azimut]

• [ ] add a cache for sqlite3 db
  • a github cache volume through a github action
  • manual github release
  • automatic github release?
• [ ] download feed only if not found in .db or .db not in fs
• [ ] before download check with HTTP Last-Modified or something similar
• [ ] still inform errors
• [ ] save cache back
• [ ] rarely fetch, rarely updated feeds

[azimut]

continuation of #5

[azimut]

changes

• add a feeds.lastfetch column with the date of last time tried to fetch new entries

possible steps

• load sqlite into a feeds structure
• fetch
• save feeds

[azimut]

should be done, added a actions/cache and logic to use Last-Modification and Etag to monitor changes if I need or not to refetch a feed.

Still might be rough edges. Like some feeds not returning those fields.

• might be I could add content-length
• and/or decide to add better logic based on which fields are present or not
• and/or add all header into json column (for easier non-destructive updates on headers logic)