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.lock

@@ -1817,6 +1817,16 @@ version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
+[[package]]
+name = "mime_guess"
+version = "2.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7c44f8e672c00fe5308fa235f821cb4198414e1c77935c1ab6948d3fd78550e"
+dependencies = [
+ "mime",
+ "unicase",
+]
+
 [[package]]
 name = "minimal-lexical"
 version = "0.2.1"
@@ -2678,6 +2688,7 @@ dependencies = [
  "hyper-util",
  "js-sys",
  "log",
+ "mime_guess",
  "percent-encoding",
  "pin-project-lite",
  "quinn",
@@ -3640,6 +3651,7 @@ dependencies = [
  "directories",
  "httpmock",
  "keyring",
+ "mime_guess",
  "open",
  "rand 0.10.3",
  "ratatui",
@@ -3678,6 +3690,12 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "unicase"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbc4bc3a9f746d862c45cb89d705aa10f187bb96c76001afab07a0d35ce60142"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.27"