feat: automatic date-based build number (YYYY.MM.DD.0.0.<n>)

User wants build numbers to always follow this format, incrementing
<n> across multiple builds on the same calendar day and resetting to 1
on a new day - not a manually-edited fixed string, and not the CI run
counter (which just uploaded a build as '51', unrelated to the real
versioning scheme).

Added next_build_version, which persists {date, build_number} to a
fixed path under this CI user's home directory on the Mac mini runner
(~/ci-build-version-state/pedifoods.json) - state has to live outside
the per-run checkout, since every CI run gets a fresh, throwaway clone
under .cache/act/<random-hash>/. assemble now passes this as the
CURRENT_PROJECT_VERSION xcarg instead of the project's committed value,
so every build gets a fresh, correctly-formatted, ever-increasing
version automatically.

fastlane/Fastfile

@@ -1,8 +1,32 @@
 # This file contains the fastlane.tools configuration for the PediFoods iOS app.
 # You can find the documentation at https://docs.fastlane.tools
 
+require "date"
+require "json"
+require "fileutils"
+
 default_platform(:ios)
 
+# Build number scheme: "YYYY.MM.DD.0.0.<n>" - <n> increments across
+# builds made on the same calendar day, resets to 1 on a new day.
+# Needs somewhere to remember "the last <n> used, and for which day",
+# and the per-run checkout under .cache/act/<random-hash>/ can't be
+# that place - each CI run gets a fresh, throwaway clone, so anything
+# written there is gone by the next run. State lives instead at a fixed
+# path under this CI user's home directory on the Mac mini runner,
+# which is the same machine/user across every run.
+def next_build_version
+  state_path = File.expand_path("~/ci-build-version-state/pedifoods.json")
+  FileUtils.mkdir_p(File.dirname(state_path))
+
+  today = Date.today.strftime("%Y.%m.%d")
+  state = File.exist?(state_path) ? JSON.parse(File.read(state_path)) : {}
+  build_number = (state["date"] == today) ? state["build_number"].to_i + 1 : 1
+
+  File.write(state_path, JSON.generate({ "date" => today, "build_number" => build_number }))
+  "#{today}.0.0.#{build_number}"
+end
+
 lane :tests do
   run_tests(
     scheme: "PediFoods",
@@ -17,19 +41,18 @@ lane :assemble do |options|
   # baked directly into PediFoods.xcodeproj's own project settings - not
   # overridden here.
   #
-  # CURRENT_PROJECT_VERSION is likewise never overridden here - it's
-  # whatever is committed in the project (manually bumped, e.g.
-  # "2026.09.11.0.0.1"). A prior version of this lane overrode it with
-  # the CI job's own run number (BUILD_NUMBER = github.run_number-style
-  # counter) to guarantee a unique, ever-increasing build number per
-  # run - but that silently replaced the real, meaningful version with
-  # an unrelated small integer (a build uploaded as "51" instead of the
-  # intended "2026.09.11.0.0.1"). Trusting the committed value means
-  # re-running CI against the same commit without bumping
-  # CURRENT_PROJECT_VERSION first will make TestFlight/App Store reject
-  # the upload as a duplicate build number - a clear, safe failure,
-  # which is the correct behavior for a manually-versioned project.
-  xcargs = "-skipPackagePluginValidation -skipMacroValidation"
+  # CURRENT_PROJECT_VERSION IS overridden here, with next_build_version
+  # (see top of file) rather than the project's own committed value.
+  # Earlier versions of this lane either used the committed value as-is
+  # (fine until you forget to bump it and Apple rejects a duplicate
+  # build number) or overrode it with the CI job's raw run-number
+  # counter (BUILD_NUMBER = github.run_number-style, which silently
+  # uploaded a build as "51" with no relation to the real version at
+  # all). next_build_version keeps the real date-based scheme and
+  # bumps only the last component automatically, so every push
+  # is guaranteed a fresh, correctly-formatted, ever-increasing build
+  # number with no manual edit needed before each run.
+  xcargs = "-skipPackagePluginValidation -skipMacroValidation CURRENT_PROJECT_VERSION=#{next_build_version}"
 
   build_app(
     scheme: "PediFoods",