* fix(desktop): keep the pre-session model pick selected in the picker
The composer picker derived its "current" row from `model.options ?? store`,
so model.options always won. Pre-session that query returns the PROFILE
DEFAULT, not the sticky composer pick — so selecting a model before a session
exists left the checkmark (and the picker's "current" line) on the default,
making the pick look ignored even though the pill updated.
Add `currentPickerSelection()`: with a live session the gateway's model.options
is authoritative; pre-session the sticky `$currentModel`/`$currentProvider`
wins, falling back to options. Wire it into ModelMenuPanel and ModelPickerDialog.
* feat(desktop): global reasoning/speed defaults in Settings → Model
The composer picker is now sticky-UI/per-session only and never writes the
profile default (#46959), but Settings → Model had no reasoning/speed control
and `agent.reasoning_effort` wasn't in the curated config surface at all
(`service_tier` was buried in Advanced) — so there was nowhere to set the
profile default that crons/subagents/messaging resolve from.
Add capability-gated Reasoning (effort) + Fast controls beside the main model,
gated by the applied model's reported capabilities (reasoning defaults on, fast
off when unreported — same as the composer). They read/write `agent.reasoning_effort`
and `agent.service_tier` by round-tripping the config record, matching the
gateway's value semantics (service_tier "fast"/"priority"/"on" ⇒ fast).
* refactor(desktop): don't open the reasoning select from its row label
A <label> wrapping the Select forwarded text clicks to the trigger, opening
the dropdown unexpectedly. Plain row for reasoning; Fast stays a <label> so
clicking its text toggles the switch (expected for a checkbox-like control).
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