Render authored Descriptive Books and persist random Age seasons (#40)

docs/SERENE_SEASONS_COMPATIBILITY.md

@@ -13,6 +13,7 @@ Serene Seasons 10.1.0.8 has no public dynamic-dimension registration hook, so th
 3. Without restarting or reconnecting, travel into the Age and check `/season get`; change its season with `/season set mid_winter` and check the Overworld and another Age separately.
 4. Reconnect another client and confirm it receives the same whitelist. Restart the server and confirm both the whitelist entry and the Age's season persisted.
 5. Build separate Ages with No Seasons, Seasons, and each Eternal page. Confirm No Seasons stays absent from Serene's whitelist, Seasons advances, and each Eternal Age remains in its named mid-season across several in-game days, a reconnect, and a server restart. Verify the Overworld still advances normally. The Eternal page should not stop the Age's sun or moon. With Serene removed, No Seasons should still bind, but the other five pages should refuse to bind with a clear message.
+6. With Serene installed and `auto_whitelist_ages=true`, create several new Link-Panel-only Ages and Ages with symbols but no season page. `/rivencraft age list` shows each saved random `season:` choice. Check that No Seasons is absent from Serene's whitelist, Seasons advances, and each Eternal choice holds its season. Reopen the world and confirm the listed choices do not change. Without Serene, create another unpaged Age and confirm the list has no saved season choice for it.
 
 For a local development run, `./gradlew runClient -PwithSereneSeasons=true` adds these two mods only to that run. The published Rivencraft jar does not include or require them.
 
@@ -31,7 +32,7 @@ An Age may specify one of six mutually exclusive seasonal modes:
 | Eternal Fall | Hold this Age in fall/autumn. |
 | Eternal Spring | Hold this Age in spring. |
 
-The six pages are available in the Season creative tab and the same page feed used by JEI. The writing grammar accepts at most one seasonal page, and its choice is saved in the Age plan. No Seasons removes that Age's ID from Serene's whitelist, even if it was previously enrolled; the other explicit pages enroll it regardless of the automatic-enrollment setting. An Age without a seasonal page follows the server's `auto_whitelist_ages` setting. If Serene Seasons is absent, No Seasons remains valid, but the other five pages reject **new** Age creation with a missing-dependency message rather than silently doing nothing. Existing Ages remain loadable with their saved pages, though their season effects are inactive until a supported season mod returns. The Ecliptic Seasons adapter is separate future work, and only one season mod is expected to be installed at a time.
+The six pages are available in the Season creative tab and the same page feed used by JEI. The writing grammar accepts at most one seasonal page, and its choice is saved in the Age plan. No Seasons removes that Age's ID from Serene's whitelist, even if it was previously enrolled; the other explicit pages enroll it regardless of the automatic-enrollment setting. When a **new** Age has no season page and Serene Seasons is installed, Rivencraft chooses one of these six modes from the Age seed and saves that choice in the Age definition. A Link-Panel-only random Age is included. The choice does not change on reload or when the spawn moves. If Serene is absent at creation, no random seasonal modifier is assigned. Older Ages without a stored choice keep their previous normal-cycle behavior. The server's `auto_whitelist_ages=false` setting still prevents implicit (unpaged) modes other than No Seasons from enrolling the Age; explicit seasonal pages override it. If Serene Seasons is absent, No Seasons remains valid, but the other five pages reject **new** Age creation with a missing-dependency message rather than silently doing nothing. Existing Ages remain loadable with their saved pages, though their season effects are inactive until a supported season mod returns. Ecliptic Seasons integration was closed as unsupported for dynamic Ages in issue #39.
 
 For an eternal mode, Rivencraft sets Serene's per-Age saved clock to the midpoint of the chosen season and resets it before it leaves that mid-season. Clients receive Serene's normal season sync. This does not freeze the Age's day/night cycle or change the Overworld's season. Eternal Winter does not guarantee snow in every biome.
 
@@ -44,3 +45,5 @@ For an eternal mode, Rivencraft sets Serene's per-Age saved clock to the midpoin
 ## Verification so far
 
 `./gradlew build` passed for candidate 0.4.9.2, and the baseline plus archived environment GameTests passed (35 required tests). The archive now covers seasonal page visibility, exclusivity, and saved-plan persistence without Serene installed. With Serene Seasons 10.1.0.8 and GlitchCore 2.1.0.2 in the optional local runtime, the GameTest server previously crashed when Serene Seasons sent `sereneseasons:sync_season_cycle` to a GameTest mock player that had not negotiated its client payload channel. The stack trace originates in Serene Seasons' `SeasonHandler.sendSeasonUpdate`, through GlitchCore's packet handler and NeoForge's packet check. This is a GameTest mock-network limitation, not a completed absent/present compatibility check. Do not keep rerunning that suite with Serene Seasons; use the real-client test path above instead.
+
+For candidate 0.4.10.1, `./gradlew build --offline` and the focused environment archive passed (36 required GameTests). The new regression check covers omitted-page selection, explicit-page precedence, no-Serene behavior, and save/reload. Actual Serene weather, whitelisting, and eternal-season visuals still require the real-client steps above.