refactor: remove explanatory comments in favour of self-explanatory code

[marsvogel]

Follow-up to #5, which recorded the rule. This applies it to everything that was already in the repository: 43 comment lines in Swift, 27 in the workflows, plus Dependabot config, CODEOWNERS and the build-number script.

Approach

A comment was never just deleted — its content moved into a name, a structure, or a test name:

Was a comment	Is now
// Sunday = 1, Saturday = 7	enum Weekday: Int { case sunday = 1, monday, … }
for _ in 0..<7	for _ in 0..<daysPerWeek
// Hide from dock, // Create popover with calendar view, …	hideFromDock(), makeCalendarPopover(), makeStatusItem(), makeFallbackRefreshTimer(), observeDateChanges()
// Right click - show context menu / // Left click - toggle popover	showContextMenu() / togglePopoverVisibility(_:)
// Month navigation header, // Calendar grid, …	extracted subviews monthNavigationHeader, weekdayHeaderRow, calendarGrid, todayButton
index >= 5, .frame(width: 28)	firstWeekendSymbolIndex, weekNumberColumnWidth, dayColumnWidth
// 1 Jan 2026 is a Thursday, so it belongs to week 1.	testJanuaryFirstBelongsToWeekOneWhenItFallsOnAThursday()
/// An ISO-8601 calendar pinned to UTC …	utcISOCalendar

The five test methods became 14, one assertion group each, so a failure names the rule that broke.

One behavioural detail worth flagging: applicationDidFinishLaunching now builds the popover before the status item, so the button action can never reference a nil popover. The old order was safe only because everything runs synchronously on the main thread.

Kept deliberately

Comments a tool acts on: the # vX.Y.Z markers Dependabot parses on SHA-pinned actions, // swiftlint: directives, // MARK: navigation, and the .gitignore section headings. If you want the MARK lines and .gitignore headings gone too, say so and I will strip them.

Rationale that left the workflow files

Recorded here rather than in the YAML, per the rule:

• fetch-depth: 0 — the "Set build number" build phase derives CFBundleVersion from the commit count, so CI needs the full history. Now also in CONTRIBUTING.md.
• SwiftLint pinned to 0.65.0 and checksum-verified — a new lint release must not break --strict CI overnight, and a swapped release asset must not run unnoticed.
• CODE_SIGN_IDENTITY="-" — ad-hoc signing keeps the app launchable on Apple Silicon without a paid Developer ID.
• ditto instead of zip — preserves the .app bundle structure and its ad-hoc signature.
• permissions: {} at workflow level — deny-all by default, each job opts into its minimum. The release job is separate so write scopes exist only where the release is created.
• The release step checks for an existing tag so a re-run on the same commit does not hard-fail.
• CodeQL runs on PRs against main only (other base branches have no baseline to compare against), skips Markdown-only PRs, and cancels superseded runs to free macOS runner slots.
• Scripts/increment-build-number.sh is a reference copy — the script that actually runs is inlined into the Xcode build phase, because the build sandbox cannot read external files. Now in CONTRIBUTING.md.

Verification

• swiftlint lint --strict — 0 violations across 5 files (same 0.65.0 as CI).
• xcodebuild test — 14 tests, 0 failures.
• xcodebuild -target QuickWeek -configuration Release build — succeeds.
• Launched the built binary as a separate process: starts clean, no crash in applicationDidFinishLaunching.
• actionlint and shellcheck pass.