docs(03-01): complete NFL canonicalization plan

Tasks completed: 3/3
- Add NFL to canonicalize_teams.py (32 teams with division structure)
- Add NFL team abbreviation aliases to canonicalize_games.py (11 aliases)
- Add NFL stadium historical aliases to canonicalize_stadiums.py (14 stadiums)

SUMMARY: .planning/phases/03-alias-systems/03-01-SUMMARY.md

.planning/phases/03-alias-systems/03-01-SUMMARY.md

@@ -0,0 +1,98 @@
+---
+phase: 03-alias-systems
+plan: 01
+subsystem: data-pipeline
+tags: [nfl, canonicalization, aliases, teams, stadiums]
+
+# Dependency graph
+requires:
+  - phase: 01-script-architecture
+    provides: NFL_TEAMS dict in nfl.py, canonicalization script patterns
+  - phase: 02-stadium-foundation
+    provides: NFL stadium data with coordinates
+provides:
+  - NFL teams canonicalized with division structure (32 teams)
+  - NFL team abbreviation aliases for game resolution (11 aliases)
+  - NFL stadium historical aliases for sponsorship/name changes (14 stadiums)
+affects: [04-canonical-linking, game-resolution, stadium-matching]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [team-abbrev-aliases, historical-stadium-aliases, division-mapping]
+
+key-files:
+  created: []
+  modified:
+    - Scripts/canonicalize_teams.py
+    - Scripts/canonicalize_games.py
+    - Scripts/canonicalize_stadiums.py
+
+key-decisions:
+  - "Used same division ID format as other sports: nfl_afc, nfl_afc_east, etc."
+  - "Included historical relocation aliases (OAK→LV, SD→LAC, STL→LAR) for backward compatibility"
+  - "Only added stadium aliases for venues with actual name changes (skipped Soldier Field, Lambeau, etc.)"
+
+patterns-established:
+  - "NFL follows same canonicalization patterns as MLB, NBA, NHL"
+  - "Team abbreviation aliases handle both historical relocations and data source variations"
+
+issues-created: []
+
+# Metrics
+duration: 4 min
+completed: 2026-01-10
+---
+
+# Phase 3 Plan 01: NFL Canonicalization Summary
+
+**NFL added to canonicalization pipeline with 32 teams, 11 abbreviation aliases, and 14 stadium historical aliases**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-01-10T15:33:15Z
+- **Completed:** 2026-01-10T15:36:49Z
+- **Tasks:** 3
+- **Files modified:** 3
+
+## Accomplishments
+- NFL teams canonicalized with full AFC/NFC division structure (32 teams)
+- NFL team abbreviation aliases added for game resolution (handles JAC/JAX, relocations, etc.)
+- NFL stadium historical aliases added for sponsorship changes (Heinz Field→Acrisure, FedExField→Northwest Stadium, etc.)
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add NFL to canonicalize_teams.py** - `d4d0d95` (feat)
+2. **Task 2: Add NFL team abbreviation aliases to canonicalize_games.py** - `41496b6` (feat)
+3. **Task 3: Add NFL stadium historical aliases to canonicalize_stadiums.py** - `90c9cef` (feat)
+
+**Plan metadata:** (pending)
+
+## Files Created/Modified
+- `Scripts/canonicalize_teams.py` - Added NFL_TEAMS import, NFL_DIVISIONS dict, sport_mappings entry
+- `Scripts/canonicalize_games.py` - Added 11 NFL entries to TEAM_ABBREV_ALIASES
+- `Scripts/canonicalize_stadiums.py` - Added 14 NFL stadium entries to HISTORICAL_STADIUM_ALIASES
+
+## Decisions Made
+- Used same division ID format as other sports (nfl_afc, nfl_afc_east, etc.)
+- Included historical relocation aliases (OAK→LV, SD→LAC, STL→LAR) for backward compatibility with older data
+- Only added stadium aliases for venues with actual name changes (skipped Soldier Field, Lambeau Field, etc. that haven't changed)
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None
+
+## Next Phase Readiness
+- NFL canonicalization complete, ready for game resolution testing
+- Ready for 03-02-PLAN.md (MLS, WNBA, NWSL canonicalization)
+
+---
+*Phase: 03-alias-systems*
+*Completed: 2026-01-10*