feat(files): play video and audio from outside the workspace too

A clip an agent wrote inside the workspace played with a working scrub bar,
while the same file in /tmp was refused as an unsupported type. The workspace
preview classified media with its own inline extension sets and the attachment
allowlist had no media at all, so the two paths disagreed about what a video is.

- VIDEO_ATTACHMENT_EXTENSIONS and AUDIO_ATTACHMENT_EXTENSIONS now live in
  attachment-registry.ts and are imported by file-content's classification, so
  both paths answer the same. mp4/webm/mov/m4v/ogv and
  mp3/wav/ogg/oga/m4a/aac/flac/opus join the attachment allowlist.
- Real MIME types for those extensions. Without one the raw route falls back to
  application/octet-stream, which a <video> refuses to decode: the player
  renders and then does nothing.
- getAttachmentType() gained the video and audio members of
  AttachmentDetectedType. Attachment cards have no per-type CSS and their
  thumbnail falls back to the type label, since the thumbnailer has no media
  branch and answers 204 rather than spawning a converter.
- The preview overlay's by-id branch renders <video>/<audio> with the same
  markup as the workspace branch, playsinline included. Serving was already
  range-aware, so seeking works.

The image-watcher keeps its own narrow detection list (png/pdf/docx/pptx), so
this does not start popping cards for every video an agent writes. Text types
that are not md or txt (.json, .log, code files) remain out of the allowlist by
choice and still report what is previewable instead.

Verified on an isolated instance: an external mp4 and mp3 both play, seek, and
report the right duration, matching the in-workspace clip exactly, and a click
on an external mp4 in the terminal opens the player with no attachment card.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -230,7 +230,7 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Attachments** (live external document references; all wiring in `file-routes.ts`): a **registry** maps a stable `attachmentId` to a realpath-resolved, extension-allowlisted absolute path, so browser requests never carry arbitrary absolute paths. ⚠️ The **magic-link scanner** (`codeman://attach?...` in terminal output) is **prompt-injectable**, so its scan path is force-confined to the session workspace; a hostile prompt could otherwise exfiltrate arbitrary host files over SSE. The security gate is an extension **allowlist**, not a blocklist. `document-conversion-limiter.ts` caps converter spawns globally: without it, N large docs detected at once fork N multi-minute processes, which is a resource-exhaustion vector. → [architecture-invariants#attachments](docs/architecture-invariants.md#attachments)
 
-**File-path links (terminal + chat)**: a path an agent prints is clickable on BOTH surfaces and opens the file-preview overlay. ⚠️ ONE pattern (`FILE_PATH_LINK_PATTERN` / `absoluteFilePathPattern()` in constants.js) feeds the xterm link provider AND the response viewer's `_linkifyFilePaths()`; a fresh instance per call, since `lastIndex` is per-object state. The chat linkifier walks TEXT NODES with DOM APIs (the source is model output; never rebuild sanitized markup as a string) and skips subtrees already inside an `<a>`. ⚠️ **An out-of-workspace path is served through the ATTACHMENT routes, not the file routes** — `file-content`/`file-raw` are workspace-confined and 404 exactly the paths agents print most (a `/tmp` capture, Claude's scratchpad), so `openFilePreview()` registers such a path via `POST /api/sessions/:id/attachments` with **`notify: false`** (suppresses only the `attachment:detected` broadcast — same guard, same routes; without it every click also popped a card announcing the file already on screen) and renders by id. The click is an explicit action on the explicit, Origin-guarded route, which is what distinguishes it from the force-confined magic-link scanner; the extension allowlist is unchanged. → [architecture-invariants#file-path-links-terminal--response-viewer](docs/architecture-invariants.md#file-path-links-terminal--response-viewer)
+**File-path links (terminal + chat)**: a path an agent prints is clickable on BOTH surfaces and opens the file-preview overlay. ⚠️ ONE pattern (`FILE_PATH_LINK_PATTERN` / `absoluteFilePathPattern()` in constants.js) feeds the xterm link provider AND the response viewer's `_linkifyFilePaths()`; a fresh instance per call, since `lastIndex` is per-object state. The chat linkifier walks TEXT NODES with DOM APIs (the source is model output; never rebuild sanitized markup as a string) and skips subtrees already inside an `<a>`. ⚠️ **An out-of-workspace path is served through the ATTACHMENT routes, not the file routes** — `file-content`/`file-raw` are workspace-confined and 404 exactly the paths agents print most (a `/tmp` capture, Claude's scratchpad), so `openFilePreview()` registers such a path via `POST /api/sessions/:id/attachments` with **`notify: false`** (suppresses only the `attachment:detected` broadcast — same guard, same routes; without it every click also popped a card announcing the file already on screen) and renders by id. The click is an explicit action on the explicit, Origin-guarded route, which is what distinguishes it from the force-confined magic-link scanner. ⚠️ **Media extensions are single-sourced** (`VIDEO_ATTACHMENT_EXTENSIONS`/`AUDIO_ATTACHMENT_EXTENSIONS` in `attachment-registry.ts`, imported by `file-content`'s classification) so a clip plays the same in or out of the workspace; a player needs all THREE of allowlist + a real `MIME_TYPES` entry (octet-stream renders a dead player) + the range-aware body. The image-watcher keeps its own narrow detection list, so this does not card every video an agent writes. → [architecture-invariants#file-path-links-terminal--response-viewer](docs/architecture-invariants.md#file-path-links-terminal--response-viewer)
 
 **Filesystem path picker** (Link Existing "Browse" + the mobile keyboard's `📁 Path` key): lazy one-directory browsing via `GET /api/filesystem/browse`, with `GET /api/filesystem/preview` for the tapped file. Inserts the path **without** Enter, so the prompt is never submitted; the sibling `⌫ All` key clears only the unsent prompt and must never send the agent's `/clear`. ⚠️ This is a **second file-serving surface and inherits neither the attachment confinement nor its ownership scoping** — it allowlists Home, `CASES_DIR`, `/mnt/d` and `CODEMAN_FILE_PICKER_ROOTS`, blocks sensitive trees, and rejects symlink escapes **after** `realpath`. ⚠️ The optional `sessionId` is an ownership boundary that must be `canAccessOwned`-checked by hand (it does not go through `findSessionOrFail`), and in multi-user mode a non-admin gets only their own `userSpacePath` as a root: per-user spaces live INSIDE `homedir()`, so a `Home` root exposes every other user's workspace. Previews go through the same global conversion limiter, and Markdown/TXT/JSON are served as inert `text/plain`. → [architecture-invariants#filesystem-path-picker](docs/architecture-invariants.md#filesystem-path-picker)