Media uploads: photos, video and audio

Attach files from the new Media field (path prompt with Tab completion,
or paste/drop paths) or by URL. Files go to the server's media endpoint
(q=config media-endpoint, multipart 'file', 201 Location) in the
background; publishing waits for them. The extension picks the photo,
video or audio property; photos can carry alt text ({value, alt}).
Edits replace or delete a media property only when it changed. Notes
with media need no text. Warns when q=config lists post types without
video or audio.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.toml

@@ -9,11 +9,12 @@ base64 = "0.23.1"
 clap = { version = "4.6.7", features = ["derive"] }
 directories = "6.0.0"
 keyring = { version = "3", features = ["sync-secret-service", "crypto-rust"] }
+mime_guess = "2"
 open = "5.4.5"
 rand = "0.10.3"
 ratatui = "0.30.2"
 ratatui-textarea = "0.9.4"
-reqwest = { version = "0.13.5", default-features = false, features = ["blocking", "json", "rustls", "form", "query"] }
+reqwest = { version = "0.13.5", default-features = false, features = ["blocking", "json", "rustls", "form", "query", "multipart"] }
 scraper = "0.29.0"
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.154"