fix: serialize range fields as bracket literals, symmetric with writes

[npflood]

Summary

• Production evidence: curling the live plant endpoint shows the 7 range fields (nAccumulationRange, biomassProductionRange, optimalTemperatureRange, optimalRainfallRange, seasonalityDaysRange, optimalAltitudeRange, phRange) rendering as Ruby Range#to_s output -- e.g. '5.5..7.0', '600...1201', '0...Infinity' -- while CreatePlant/UpdatePlant only accept and document Postgres-style bracket literals ('[min,max]'). Reads and writes were asymmetric since these fields shipped, so the admin SPA's range parser renders a blank input for every existing value.
• Adds RangeLiteral (app/services/range_literal.rb), a pure serializer symmetric with the write side:
  • Integer ranges (int4range) round-trip through Postgres canonicalized to inclusive-lower/exclusive-upper (an editor's "[500,2000]" comes back from the database as the Ruby Range 500...2001), so a finite exclusive upper bound is decremented by 1 back to the inclusive value that was actually typed.
  • Numeric ranges (numrange) preserve whatever inclusivity was written (Postgres doesn't canonicalize continuous ranges), formatted via BigDecimal#to_s('F') to avoid engineering notation (BigDecimal#to_s/#inspect defaults render "0.55e1"), with a trailing ".0" stripped so a whole number like 7.0 renders "7".
  • Unbounded bounds (nil or infinite) render as an empty side, always closed with "]" ("[10,]", "[,100]"), never ")".
• Wires it into PlantType and VarietyType via Types::Concerns::RangeLiteralFields, which define_method's the 7 resolvers from the single field list already declared in Mutations::Concerns::RangeLiteralValidation::RANGE_FIELDS -- one source of truth for "the 7 range fields", no new field declarations (those already existed).
• Also fixes RecordDraftInfoType#author/#last_editor: Principal#display_name is nil for principals created by resolve_actor's upsert (application_controller.rb) -- it never passes a display name -- so this field rendered "Unknown" for the common case in staging. Falls back to email. No new exposure: draft is gated by update?, and editors who can see it already see the record's owner/creator email via ownedBy/createdBy.

Test plan

• docker compose run --rm -e RAILS_ENV=test web bundle exec rspec -- full suite green, 2324 examples, 0 failures.
• spec/contracts/** (mobile compatibility contracts) verified to carry zero range-field assertions before this change, and still green after -- the mobile app's locked-in GraphQL documents are unaffected by this fix.
• New specs (TDD): spec/services/range_literal_spec.rb (integer decrement, unbounded both sides, BigDecimal formatting incl. the scientific-notation trap, nil, exclusive-numeric paren form), spec/mutations/range_literal_round_trip_spec.rb (schema-level write-then-read round trips for "[10,]", "[500,2000]", "[5.5,7.0]" numrange, and a DRAFT-perspective read via saveAsDraft: true + plant(perspective: DRAFT), plus a VarietyType check), spec/types/record_draft_info_type_spec.rb (display_name present / nil / blank -> email fallback).
• docker compose run --rm web bundle exec rubocop -- clean, 730 files, no offenses.
• docker compose run --rm web bundle exec rails graphql:schema:dump -- diff is exactly the two RecordDraftInfo.author/.lastEditor description updates; committed.

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