Add Nexus alliance and shared-victory practice

Expand the internal introduction to nine lessons and seven Basic exercises. The four-player Nexus example teaches incoming consent, outgoing accepted and unanswered offers, withdrawal, unilateral breaks and the ordinary three-solo/four-allied stronghold target. Formation shows prospective progress; victory appears only at an explicit later Mentat check on the unchanged teaching board. Fixed responses demonstrate legal choices without refining live AI.

Extract ordinary pairing into quoteNexusAlliance used by both practice and engine. Keep phase and Homeworld checks, alliance dates, Nexus-card forfeiture, readiness and history in the authoritative engine. Use production strongholdProgress and quoteVictory for the example; physical forces remain separately owned. No mode, expansion or publication gate changes.

Version 4 practice saves migrate all five v1, seven v2 and eight v3 lesson identities and preserve prior auction, movement, combat, Traitor and collection choices. Alliance inputs are whitelisted and semantically replayed, with impossible action sequences and phase order rejected. Nine new regression tests cover helper immutability, live engine side effects, all 24 offered practice combinations, prior-version migration and saved continuation. Existing Nexus-card forfeiture tests also pass.

Independent review found no material defect. Required types, lint, 4934 offline tests and production build pass on stable final source. Browser checks confirm old completed-auction migration, keyboard consent, formed and pending refresh restoration, withdrawal/break, closed-Nexus controls, three-stronghold shortfall and four-stronghold joint win with saved result. Controls fit a 390px viewport at 309px wide and at least44px high; viewport reset. No external lesson links. Screenshot capture remains unavailable, so visual screenshot acceptance remains unverified. Fixed lessons do not certify the full curriculum, live AI strength or all rules interactions.

The local development server was confirmed stopped by refused localhost connection and no matching processes. Started it once against the existing database without migration/reset. The existing K2V47CSN QA seat restored in setup with owning Atreides private hand/Traitors and rival privacy intact; its Hard Guild and circle6 remained visible. All 1337 rooms, 2805 seats and every original recovery/entry/handover/delegation/migration row are unchanged. SQLite integrity and foreign keys pass. No human play was interrupted, no recurring automation installed and no usage check or AI calibration run. HTTP/auth/schema source did not change; offline checks include recovery tests, and no broad HTTP suite was rerun.

Private evidence: 20260921-alliance-practice. Full rules, expansion, multiplayer and presentation goal remains incomplete.
Verified source tree: 9c74a3141aca4e049e0734209b96f68ee0e6d0e127a155a2a7562a79ea8a1a6b

docs/CURRENT_STATUS.md

@@ -1,27 +1,27 @@
 # Current development status
 
-Updated 20 September 2026. **The full twelve-faction goal is unfinished. Basic
+Updated 21 September 2026. **The full twelve-faction goal is unfinished. Basic
 is playable; public Advanced and unfinished expansion/module starts remain
 gated.** Prototypes do not open completion or publication gates.
 
 ## Current checkpoint and work
 
-Latest delivered checkpoint: `b9718ac`, [lobby AI configuration](LOBBY_AI_CONFIGURATION.md).
-Types, lint, **4,916 offline tests**, production build and **46 HTTP tests** passed.
-All 1,262 baseline rooms and 2,644 seats stayed unchanged; the new preservation
-baseline contains 1,337 rooms and 2,805 seats. No restart was needed.
-The preceding `b21b2bc` connects [one-use AI permission](SEAT_AI_PERMISSION.md).
-The `8f7a62c` policy checkpoint removed the
-usage cutoff and deferred AI refinement until feature completion, with three
-adjacent 75% win-rate targets. Earlier evidence remains in the
-[implementation history](IMPLEMENTATION_STATUS.md).
+Latest delivered checkpoint: `b7ec940`, [interactive bidding](INTERACTIVE_INTRODUCTION.md).
+Types, lint, **4,925 offline tests** and production build passed. All 1,337 rooms,
+2,805 seats and existing recovery/entry/handover/delegation rows stayed unchanged.
+The preceding `b9718ac` connects [lobby AI configuration](LOBBY_AI_CONFIGURATION.md)
+and `b21b2bc` connects [one-use AI permission](SEAT_AI_PERMISSION.md).
+The `8f7a62c` policy checkpoint removed the usage cutoff and deferred AI refinement
+until feature completion, with three adjacent 75% win-rate targets. Earlier
+evidence remains in the [implementation history](IMPLEMENTATION_STATUS.md).
 
-Current work: [interactive bidding](INTERACTIVE_INTRODUCTION.md) connects the
-eighth lesson to shared ordinary-auction calculations, private purchase inspection
-and versioned saved practice. No AI strategy is changed. Independent review and
-final browser/check/build/preservation evidence belong to the source-bound private
-report and Git message. Alliances, faction/Advanced/expansion teaching and broader
-disconnected-seat acceptance remain unfinished.
+Current work: [interactive alliance practice](INTERACTIVE_INTRODUCTION.md) adds
+the ninth lesson, ordinary Nexus consent/break choices and later shared stronghold
+victory through production quotes. Versioned practice migrates all earlier lesson
+positions and choices. No AI strategy is changed. Final independent review,
+browser/check/build/preservation and Git evidence belong to its private report.
+Alliance powers, faction/Advanced/expansion teaching and broader disconnected-seat
+acceptance remain unfinished.
 
 A bounded remaining-effect audit found that the reviewed faction/Nexus candidates
 still cross recorded pending rulings. Continue independent features rather than