fix(agentsfleetd): the approval card names the fleet, not its bundle

Greptile caught this on the auto-suffix path, and it reaches further than the
report. `core.fleets.name` is the instance identity — unique per
(workspace_id, name) — while `config_json`'s name is the bundle's TRIGGER.md
declaration, identical across every fleet installed from it. Nothing rewrites
config_json when a name is server-derived or operator-overridden, because the
bundle did not change.

`FleetSession` loaded the config but not the name, so `approval_gate_park`
built its Slack card from `config.name`. A workspace running two fleets from
one bundle got two approval cards carrying the same name, neither of them the
installed fleet's — the operator approves against the wrong identity.

The session now loads the row's name beside the config and the card reads it.
That covers the operator-override path too, which carried the same defect
before the auto-suffix existed — and its comment asserted the premise that
allowed both ("nothing reads config_json's name downstream"), so that is
corrected rather than left as a trap for the next reader.

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