feat(app): attach any file and deliver unsupported ones by path - #49467

Stacked on #49466.

Drop, paste, or pick any file into the composer. If the selected model reads it natively, nothing changes. Otherwise, instead of the "Unsupported attachment" toast, the model gets a path it can open with its tools.

Composer with a .pptx attached	Sent message, remote server, GPT-5.6 Sol reading the zip via unzip -l

flowchart TD
  A[Attachment on submit] --> B{Model reads<br/>this MIME natively?}
  B -- "text/plain · png/jpeg/gif/webp (image input) · pdf (pdf input)" --> C["inline: data: URI in files (unchanged)"]
  B -- no --> D{Server local and<br/>source path known?}
  D -- yes --> E["path = source path"]
  D -- no --> F["fs.write → &lt;info.paths.tmp&gt;/uploads/&lt;uuid&gt;/&lt;name&gt;"] --> G["path = resolved server path"]
  E & G --> H["text += Attached file: `&lt;path&gt;`<br/>metadata.attachments += { name, mime, path }"]

• Decided at submit in packages/app/src/composer/attachments/deliver.ts, so it uses the model selected at send time and covers prompts, custom commands, and queued-prompt edits.
• Same AttachmentCard everywhere: in the composer before sending, and on the sent message. The sent message renders it from metadata.attachments (same mechanism as review comments), so it survives reloads and other clients; displayText stays the typed text while the model sees:

How many .svg files are in the attached zip? Answer with a number only.
Attached file: `/tmp/opencode/uploads/0960c4cc-…/opencode-brand-assets.zip`

• Verified end to end from this PC against a server on a VPS: 20 531-byte zip uploaded raw, sha256 matched on the server, model listed the archive and reported the VPS hostname.
• Removed: static accepted-type lists (composer, hidden <input accept>, desktop picker filter, file-picker.ts) and prompt.toast.pasteUnsupported.* in all locales.