P06-01: Implement approved A06 finite Mana reserve (MP-01-r02 recommended)

Initial 100, capacity 300, world tree +20 per 10 game minutes. Each boundary
pays registered upkeep demand before storing surplus; overflow is discarded
and recorded, 0 stops the whole tower. Furnace offers are judged after
generation and demand payment. New saves carry mana_reserve and Operations
rollback includes it; legacy saves keep a 0..300 amount and reject others.

Outage tests that relied on Mana 0 persisting now hold the outage with a
disabled demand sink, since the world tree recovers at the next boundary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/plans/original-completion-2026-10-02/plan_validation.json

@@ -84,7 +84,7 @@
       "passed": true
     },
     {
-      "name": "all5_confirmed_decisions",
+      "name": "all6_confirmed_decisions",
       "passed": true
     },
     {
@@ -238,7 +238,7 @@
     "build_atomic_requirements.py": "6d6ea9e4216372dbd0f9fed3f885a4481b21a3f539a26f64cf98a6830af984c5",
     "build_facility_value_contracts.py": "35027b23ce75ce9e4e0cdfc5132fd2eb771ba9f598d97750d7ecf9ecb257f769",
     "current_evidence_links.json": "db1837bcc8497201134297e312f4b266a297102285307ec3075d4e23632e26c2",
-    "decisions.json": "ad0673051b0fa601e525f05128e0b11e2dddd9d4bae6a3e0170bbf47da35efe9",
+    "decisions.json": "927065d9f840e68667d10998d26eb5d04f5591d9f24082106d082e51d5af5c96",
     "facility_value_contracts.json": "447388ba03a29bfac25f2bcd068665aedbb07ba7641ce86f2db93d44f4c9f326",
     "facility_value_contracts_validation.json": "bf490a9ca585c48fc318e76c4a069ef244827d828d46e6415399f7710590dd16",
     "performance_audit.json": "0b630b15a392c3e0366f1362bfe4ddacb968f915f54549f82e4d6fa315384762",
@@ -251,7 +251,7 @@
     "source_atomic_coverage.json": "2ab7b9e6a2536ef248d4f7ccd695bf75a082b47018aca7a5a1b6b706fe1907bc",
     "validate_atomic_requirements.py": "5b2d0b7d72cb124830fbb0a12d1434e6db698148cc5263d33fd5bd7c2953a1e0",
     "validate_facility_value_contracts.py": "91640e2a76cd6cc9186f7b85c0bf379b24b6cac0d48962815235ee628e7ae43e",
-    "validate_plan.py": "23678227d9b3c556f1bd903f4b5b3147c4a82ce5085e10055481026803451b80",
+    "validate_plan.py": "e31316aff6c814d1e1660a97b91cc0c0016d2b722c4d4092a71859a85bd0e65d",
     "validator_update_checks.json": "f997d0f3de2cea29550840b1d5cb23647d64f81329de46758551e2b6c8fecc27",
     "work_packages.json": "1913634b33ca25bec6d5a0a6a4d3d9258b7fd4c9c79c9ab426f21ac2b11c6e81"
   }