docs(01): create phase 1 plans

Phase 01: Semantic Position Model
- 2 plans in 2 waves
- Wave 1: SortOrderProvider + Trip day derivation (parallel-ready)
- Wave 2: Tests verifying persistence behavior

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/phases/01-semantic-position-model/01-01-PLAN.md

@@ -0,0 +1,155 @@
+---
+phase: 01-semantic-position-model
+plan: 01
+type: execute
+wave: 1
+depends_on: []
+files_modified:
+  - SportsTime/Core/Models/Domain/SortOrderProvider.swift
+  - SportsTime/Core/Models/Domain/Trip.swift
+autonomous: true
+
+must_haves:
+  truths:
+    - "Games get sortOrder derived from game time (minutes since midnight + offset)"
+    - "Inserting between two items produces midpoint sortOrder"
+    - "Day number can be calculated from any date given trip start date"
+  artifacts:
+    - path: "SportsTime/Core/Models/Domain/SortOrderProvider.swift"
+      provides: "sortOrder calculation utilities"
+      exports: ["initialSortOrder(forGameTime:)", "sortOrderBetween(_:_:)", "sortOrderBefore(_:)", "sortOrderAfter(_:)", "needsNormalization(_:)", "normalize(_:)"]
+    - path: "SportsTime/Core/Models/Domain/Trip.swift"
+      provides: "Day derivation methods"
+      contains: "func dayNumber(for date: Date) -> Int"
+  key_links:
+    - from: "SortOrderProvider"
+      to: "ItineraryItem.sortOrder"
+      via: "Utilities compute values assigned to sortOrder property"
+      pattern: "sortOrder.*=.*SortOrderProvider"
+---
+
+<objective>
+Create the sortOrder calculation utilities and day derivation methods that Phase 1 depends on.
+
+Purpose: Establish the foundational utilities for semantic position assignment. Games need sortOrder derived from time, travel/custom items need midpoint insertion, and items need day derivation from trip dates.
+
+Output: `SortOrderProvider.swift` with all sortOrder utilities, `Trip.swift` extended with day derivation methods.
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/execute-plan.md
+@~/.claude/get-shit-done/templates/summary.md
+</execution_context>
+
+<context>
+@.planning/PROJECT.md
+@.planning/ROADMAP.md
+@.planning/STATE.md
+@.planning/phases/01-semantic-position-model/01-RESEARCH.md
+
+# Existing source files
+@SportsTime/Core/Models/Domain/ItineraryItem.swift
+@SportsTime/Core/Models/Domain/Trip.swift
+</context>
+
+<tasks>
+
+<task type="auto">
+  <name>Task 1: Create SortOrderProvider utility</name>
+  <files>SportsTime/Core/Models/Domain/SortOrderProvider.swift</files>
+  <action>
+Create a new file `SortOrderProvider.swift` with an enum containing static methods for sortOrder calculation.
+
+Include these methods (as specified in 01-RESEARCH.md):
+
+1. `initialSortOrder(forGameTime: Date) -> Double`
+   - Extract hour and minute from game time
+   - Calculate minutes since midnight
+   - Return 100.0 + minutesSinceMidnight (range: 100-1540)
+   - This ensures games sort by time and leaves room for negative sortOrder items
+
+2. `sortOrderBetween(_ above: Double, _ below: Double) -> Double`
+   - Return (above + below) / 2.0
+   - Simple midpoint calculation
+
+3. `sortOrderBefore(_ first: Double) -> Double`
+   - Return first - 1.0
+   - Creates space before the first item
+
+4. `sortOrderAfter(_ last: Double) -> Double`
+   - Return last + 1.0
+   - Creates space after the last item
+
+5. `needsNormalization(_ items: [ItineraryItem]) -> Bool`
+   - Sort items by sortOrder
+   - Check if any adjacent gap is less than 1e-10
+   - Return true if normalization needed
+
+6. `normalize(_ items: inout [ItineraryItem])`
+   - Sort by current sortOrder
+   - Reassign sortOrder as 1.0, 2.0, 3.0... (integer spacing)
+   - Updates items in place
+
+Use `Calendar.current` for date component extraction. Import Foundation only.
+  </action>
+  <verify>
+File exists at `SportsTime/Core/Models/Domain/SortOrderProvider.swift` with all 6 methods. Build succeeds:
+```bash
+xcodebuild -project SportsTime.xcodeproj -scheme SportsTime -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.2' build 2>&1 | tail -20
+```
+  </verify>
+  <done>SortOrderProvider.swift exists with all 6 static methods, project builds without errors</done>
+</task>
+
+<task type="auto">
+  <name>Task 2: Add day derivation methods to Trip</name>
+  <files>SportsTime/Core/Models/Domain/Trip.swift</files>
+  <action>
+Extend the existing Trip struct with day derivation methods in a new extension at the bottom of the file.
+
+Add these methods:
+
+1. `func dayNumber(for date: Date) -> Int`
+   - Use Calendar.current to get startOfDay for both startDate and target date
+   - Calculate days between using dateComponents([.day], from:to:)
+   - Return days + 1 (1-indexed)
+
+2. `func date(forDay dayNumber: Int) -> Date?`
+   - Use Calendar.current to add (dayNumber - 1) days to startDate
+   - Return the resulting date
+
+Add a comment block explaining:
+- Day 1 = trip.startDate
+- Day 2 = startDate + 1 calendar day
+- Games belong to their start date (even if running past midnight)
+
+These methods complement the existing `itineraryDays()` method but work with raw Date values rather than the Trip's stops structure.
+  </action>
+  <verify>
+Build succeeds and new methods are callable:
+```bash
+xcodebuild -project SportsTime.xcodeproj -scheme SportsTime -destination 'platform=iOS Simulator,name=iPhone 17,OS=26.2' build 2>&1 | tail -20
+```
+  </verify>
+  <done>Trip.swift has dayNumber(for:) and date(forDay:) methods, project builds without errors</done>
+</task>
+
+</tasks>
+
+<verification>
+1. Both files exist and contain expected methods
+2. `xcodebuild build` succeeds with no errors
+3. SortOrderProvider methods are static and accessible as `SortOrderProvider.methodName()`
+4. Trip extension methods are instance methods callable on any Trip value
+</verification>
+
+<success_criteria>
+- SortOrderProvider.swift exists with 6 static methods for sortOrder calculation
+- Trip.swift extended with dayNumber(for:) and date(forDay:) methods
+- Project builds successfully
+- No changes to existing ItineraryItem.swift (model already has correct fields)
+</success_criteria>
+
+<output>
+After completion, create `.planning/phases/01-semantic-position-model/01-01-SUMMARY.md`
+</output>