VSN-2707: Unify table layout — widen columns, flex Actions track, center Actions header/icons

Summary

Applies a unified layout pass to every CSS-grid split-panel table across the app so header and body stay pixel-aligned and no empty space is left on the right.

Changes

• Column widths: widened COLUMN_MIN_WIDTHS per table so content fills the viewport (fleet / RH / exploitation / admin-config / email / client / establishment / driver / etc.)
• Flex Actions track: trailing Actions column changed from fixed Npx to minmax(Npx, 1fr) so it absorbs leftover viewport width and kills the right-side gap
• Actions alignment: Actions header + icons centered everywhere (align: 'center' on head entries, justify-center on row action cells)
• Header support: shared TableHeadCustom now honors align: 'center' via justify-center
• Grid drift fix: filter id === '' phantom tracks from both grid builders and row loops, use fixed px for all non-Actions columns (only last track is flex) so separate header/body grids resolve tracks identically
• Missing Actions headers: added synthetic Actions head columns where tables were rendering icons without a label
• Action icons: kept colored edit (orange) / copy (blue) / toggle (purple), removed lingering opacity-50 dim rules

Scope

~100 table/row/mock/hook files updated across:

• exploitation (infrastructure, class-level)
• rh (salarié, document, formulaire, recrutement, rdv-annuel, absence)
• fleets (vehicle, revision, réparation, incident, carburant, kilometrage, fuelcard, fuelSupplier, brand-model, supplierType, affectation, anomaly-configuration)
• admin-config (agent-role, email, notification)
• chauffeur (listeChauffeur, roadmap, suivi-trajet)
• client, contract, establishment, usager, circuit, avenant, absence, staff/absence

Plus shared: table-head.tsx, table-pin-utils.ts.

Closes VSN-2707