feat(tui): add footer to choose every message footer detail the same way - #53877

Only prompts (/timestamps) and assistant turn footers (/turn-times,
turn_timing.time) can show when something happened. Tool calls,
thinking blocks, text blocks, errors and compactions never do, so a
long run gives no way to see when a step finished or how long a tool
call ran.

Add a `timestamps` option to tui.json naming the entry types that show
a timestamp: "all", "none", a comma-separated list such as
"user,tool", or an array. The types are user, assistant, text,
reasoning, tool, error and compaction. Tool calls show when they
finished and how long they ran; thinking blocks put the time before
their existing duration; text blocks and errors get a muted time line;
the compaction divider gets the time in its title. All use
Locale.todayTimeOrDateFirst, like the turn footer.

Unset, nothing changes: /timestamps, /turn-times and turn_timing.time
work and persist exactly as before. Set, the list decides every type
on each start and overrides turn_timing.time; /timestamps and
/turn-times still flip prompt and turn times, until the TUI exits. A
kv-wins rule would make the option dead for most existing installs:
kv.json usually already holds "timestamps", because the kv store
persists its in-memory defaults alongside any other write.

The JSON schema description documents every value, since opencode
ships no commented tui.jsonc template.

Message footers name the model by its display name only, so the same
model served through two providers (openai and a gateway clone, a
direct API key and a proxy) reads identically, and nothing on screen
says which provider answered a turn.

model_label in tui.json picks the label: 'name' (default) keeps the
display name; 'id' shows providerID/modelID, e.g.
anthropic/claude-sonnet-4-5, in every assistant message footer and in
the prompt's model indicator, where it replaces the model and provider
names. Variant and duration stay as they are.

Assistant message footers name the model but not the variant it ran
with, so a turn on high reasoning effort reads the same as one on the
default. The variant is stored on every message and the prompt shows
the current one, but nothing shows which one a past turn used.

footer_variant in tui.json (default false) adds the message's variant,
e.g. high or max, after the model in assistant message footers. Turns
without a variant are unchanged. Documented in tui.mdx.

A long session can only be moved through by line, page or the whole
transcript. messages_next/messages_previous exist but are unbound,
and they skip any prompt within 10 rows of the viewport top, because
they compare against a fixed threshold rather than the row they land
on. Assistant parts render without an id the scroll position could be
matched against.

Bind three levels of navigation by default, all overridable in
tui.json:

- messages_previous / messages_next (ctrl+up / ctrl+down) stop on
  every user prompt, now through the same picker as the two below.
- messages_landmark_previous / messages_landmark_next
  (ctrl+shift+up / ctrl+shift+down) stop on prompts, the last text
  part of each turn (its final response), and question, todowrite and
  task calls. Edits, reads and shell calls are left out because they
  are as dense as the blocks themselves.
- messages_block_previous / messages_block_next
  (ctrl+alt+shift+up / ctrl+alt+shift+down) stop on every prompt,
  text part, reasoning part with content, and tool call. Reasoning
  without content - an encrypted block or an empty "Thinking"
  placeholder, which GPT models emit on every step - renders as a
  bare header and is skipped.

Text, reasoning and tool boxes now carry their part id so the session
route can find them among the scrollbox children, as it already does
for user messages by message id. "Previous" and "next" are relative to
the row a navigated block lands on, one below the viewport top, so
repeated presses walk block by block; past either end the view goes
to the top or back to the bottom.

messages_first and messages_last also bind ctrl+home and ctrl+end.

Message footers grew one setting per detail, each with its own value
shape: turn_timing.time/duration are booleans, timestamps is a type
list, footer_variant is a boolean, and the agent, model and total have
no setting at all. There was also no way to see a message's ID, which
is what logs, the database and the API key everything by.

footer in tui.json has one key per detail - agent, model, variant,
time, duration, total and the new message_id - and every key takes the
same value: true/"all", false/"none", "important", or a list of entry
types from the timestamps vocabulary (user, assistant, text, reasoning,
tool, error, compaction), which may include "important". "important"
selects the landmarks ctrl+shift+up/down stops on, reusing
navigationTargets(..., "landmark"); a message-level entry counts when
the message or one of its parts is one (isLandmark in navigation.ts).
A type a key does not apply to has no effect, which each key's schema
description lists.

message_id shows the msg_ ID at the end of user and assistant footers
as plain text, so it can be selected with the mouse to copy. Time,
duration and message_id also give a turn's earlier steps a footer once
they finish, as turn_timing did.

Every tool call takes time, duration and message_id the same way,
whatever renders it - built-in, generic, plugin or MCP tools. A block
tool puts them on its own last line and an inline row after its text,
or on its own line when the arguments span lines, so a long prompt or
command cannot push them out of sight. The footer details are all
muted except the agent name, the variant included.

Unset keys keep today's behavior: turn_timing, footer_variant and
timestamps map onto footer.time, footer.duration and footer.variant
(footerSelections in config/index.tsx), and /timestamps, /turn-times
and /turn-durations persist as before. A key set in footer decides on
every start and its toggle lasts until exit, as timestamps already did.
Defaults render the upstream footer unchanged.