slosh: OSC 8 hyperlinks pass through the compositor

lib-vt tracks a hyperlink per cell and slosh dropped every one of them: the
client's terminal can only offer a link it was sent, so `ls --hyperlink`,
gcc diagnostics and friends silently lost theirs inside the session.

The link rides beside the cell -- cell_t is the shader ABI and a link is
not a colour -- as a plane of ids into an interned URI table, append-only
so an id in prev_link still means the same URI next frame (which is what
lets the diff compare ids instead of strings), and capped so a hostile pane
cannot grow it forever. URIs with control bytes are refused outright: they
are emitted verbatim inside an OSC, and a control byte in one is a way to
write escape sequences into the client's terminal. The diff wraps emitted
runs in OSC 8, closes what it opens before the frame ends, and treats a
link-only change as a change. Chrome painted over a link takes the link
with it, so a frame, modal or float across a URL is never clickable with
the pane's link; links survive scrollback with the text that carries them.

Plain-text URLs stay the outer terminal's own matcher, with the catch
documented in panes.md: under mouse capture Ghostty only offers links with
shift added to the gesture (shift+cmd hover/click), shift being its
capture escape. Wrapped URLs can never be regex-matched through a
multiplexer -- rows repaint as hard lines -- which is exactly what OSC 8
links, passing through whole, are for.

`snapshot format:"bytes"` returns the emitter's own output for a frame (a
second call is the delta): the model and the bytes are two different
things, and this codebase already paid once for asserting on one while the
other was wrong.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/scripting.md b/docs/scripting.md
index 43615a2..0074782 100644
--- a/docs/scripting.md
+++ b/docs/scripting.md
@@ -21,7 +21,7 @@ Panes and tabs are addressed by **id**, so a background tab is scriptable.
 | verb | |
 |---|---|
 | `panes` `tabs` | what exists, with ids, rects, titles, purposes, state. A pane's `tab_id` is what `move-pane` and `select-tab` want; its `tab` is where that tab sits in the strip |
-| `snapshot` | the composited screen, as JSON or `format:"text"` |
+| `snapshot` | the composited screen, as JSON, `format:"text"`, or `format:"bytes"` — the emitter's own output for this frame (a second call is the delta) |
 | `deadline` | when the session wants its next frame, in ms, or -1 |
 | `send` | bytes as if typed, decoded like input (`"data":"\\x01\\\\"`) |
 | `raw` | bytes straight into the focused pane's pty |