Adds the editable half of BRIEF §3a's mobile grid set: rename an investor
and add/edit/remove its contact pills from the mobile detail sheet.
New POST /api/fundraising/update-row is the one-row read-fresh-modify-write
twin of log-communication: it mutates only the target row's name/contacts in
the canonical grid blob server-side, then bumps the version + re-syncs the
relational tables. It never accepts a whole-grid payload, so a stale mobile
client can't clobber concurrent edits to other rows (the reason mobile avoids
the whole-grid PUT). _sanitize_fundraising_contacts whitelists the known pill
fields as the trust boundary; removing a pill is soft on the classic contacts
directory (only the grid pill + fundraising_contacts row drop).
Frontend: MobileFundraisingGrid gains an Edit bottom-sheet (name input + pill
editor with client-side dedup); money stays desktop-only. New CSS is
theme-var-only so it flips in light mode.
Verified: test_fundraising_update_row.py (24 assertions, real HTTP), full
suite 37/37, render-smoke + a 375px jsdom interaction harness green.
Keysat