Add simplified Open Practice flow and reorganize

docs/javascript-architecture.md

@@ -294,6 +294,7 @@ Owns:
 - team normalization
 - race presets
 - race wizard defaults and session generation
+- practice-only Open Practice event/session generation
 - sponsor round generation
 - event drivers / teams / team driver pool
 - qualifying/finals generation and bumps
@@ -1013,6 +1014,7 @@ Why fragile:
 High-risk functions:
 - `normalizeEvent(...)`
 - `buildRaceFormatConfigFromForm(...)`
+- `buildOpenPracticeBundle(...)`
 - `getEventDrivers(...)`
 - `getTeamDriverPool(...)`
 - `generateQualifyingForRace(...)`
@@ -1419,9 +1421,12 @@ Practical normalized shape:
   participantsConfigured: boolean,
   finalsSource: "practice" | "qualifying",
   teams: RaceTeam[]
+  practiceOnly: boolean
 }
 ```
 
+`practiceOnly: true` identifies the simplified Open Practice flow. It deliberately has no class scope or configured participants, uses an `open_practice` session, ignores `durationMin` in timing logic, and must not require qualifying/finals in race summary warnings.
+
 ### `RaceTeam`
 
 ```js
@@ -2075,6 +2080,7 @@ npm test
 
 `tests/race_timing_logic.test.js` covers:
 - race-format parsing, defaults, lap limits, participants, and teams
+- practice-only Open Practice bundle creation and persisted mode markers
 - wizard generation of practice, qualifying, and team-race sessions
 - qualifying heat generation and manual-grid-safe reseeding
 - final generation, reserved bump slots, and bump-up promotion