fix(startup): a failed startup is the session's error; a store at an older schema fails it in its own words

[cryptskii]

What

Both appliance phones sat on "STARTING RUNTIME / WARMING UP BRIDGE" with no end. Their stores were left at client schema 24 by an older build; main expects 25 and does not migrate. Nothing told the page: initialize_sdk_core set SDK_READY false and handed the error to a caller that only logged it, so the phase stayed runtime_loading, and Kotlin logged "SDK initialized" after initSdk answered false.

• A failed startup is the session's error. It is recorded as the session's fatal error, so the phase is error and the page shows Rust's reason on its error screen. A later successful startup takes back the failure it recorded; an error anyone else reported stays.
• Startup opens the client store. A store this build refuses fails startup in the store's own words. Unopened, the refusal surfaced through whatever read the store first: on Android that was the sealed-seed read, which was downgraded to a warning and re-reported as "wallet seed not unlocked". A seed vault that cannot be read now fails init as itself.
• Kotlin logs a failed initSdk as a failure.
• Deleted: initSdkV3 had no caller and declared the SDK ready after setting only the storage directory. It goes with its Kotlin declarations and InitFailed, which only it produced; Envelope field 31 is reserved.
• Ledger: §6.36 row B-START.

Verification

• dsm_sdk lib sdk::session_manager + ingress::tests on Postgres, single-threaded: 35 passed. New: a_store_at_an_older_schema_fails_startup_as_the_sessions_error, on the running fleet — a device created as wallet creation creates it, its store left as schema 24 left it (stamped 24, without the table 25 added), the process restarted; startup fails with SCHEMA RESET REQUIRED, the phase is error with that message; after the wipe the refusal names, startup succeeds and the error is gone. And a_startup_failure_is_the_sessions_error_until_a_startup_succeeds.
• Mutations: the recording dropped → the test red (runtime_loading, not error); the store open at startup dropped → red (startup answered OK). Both restored, green.
• cargo check -p dsm -p dsm_sdk --tests, cargo check -p dsm_vertical_validation, cargo ndk -t arm64-v8a check -p dsm_sdk --features jni,bluetooth: clean. ./gradlew compileDebugKotlin compileDebugUnitTestKotlin: clean. TS protos regenerated; type-check: clean.
• flow_assertions.sh, bridge_rpc_names.py, bridge_contracts_gate.sh, ci_scan.sh, enforce-guardrails.sh, ci/conformance_evidence.py: pass. make lint: passed.
• Device: an APK carrying this branch and feat(wallet): offline funding and the appliance on the send screen; balance rows state their offline allocation #1040, the native library built from crates/dsm-android-anchor (on_device_installs), installed over the data on both appliance phones (A54, 5GN), whose stores are at schema 24. Before: "STARTING RUNTIME / WARMING UP BRIDGE" with no end. After: the error screen reads ERROR: startup: init_dsm_sdk failed: Storage error: the client store: SCHEMA RESET REQUIRED: client database is version 24, this build expects 25. DSM beta does not migrate — wipe the app database and re-provision from the wallet seed.; logcat shows phase=error on both.