Rebrand alknet-vault -> alkvault

Rename the crate from alknet-vault to alkvault across source and docs:
- Cargo.toml: package name and lib name (alknet_vault -> alkvault)
- src/ doc comments and doc-test use statements
- tests/ use statements and one string literal

Convert references to non-vault alknet ADRs (003, 005, 008, 010, 014,
064) that were broken local links into @alkdev/alknet: cross-repo
references, matching the alktype sibling pattern. Local ADR/OQ
references are now proper links. Rewrote monorepo path references
(crates/alknet-vault/src/...) to the flat layout (src/...). Fixed
sdd_process.md package name (@alkdev/storage -> @alkdev/alkvault).

ADR/OQ renumbering is deferred to a subsequent pass per the alknet-
origin numbering convention. Generic prose 'vault' and type names
(VaultServiceHandle, VaultServiceError, etc.) are unchanged.

Build, 108 tests, and clippy all pass clean.

docs/architecture/questions/020-salt-kdf-and-encryption-key-derivation-method.md

@@ -5,4 +5,4 @@
 - **Door type**: One-way (key derivation method), two-way (salt field usage)
 - **Priority**: high
 - **Resolution**: The vault uses SLIP-0010 HD derivation from the BIP39 seed at path `m/74'/2'/0'/0'` to produce the AES-256-GCM encryption key — not PBKDF2. The `salt` field in `EncryptedData` is unused for key derivation (kept for wire-format compatibility with the TS predecessor). The TypeScript `@alkdev/storage` crypto module used PBKDF2 with a password + salt; data encrypted by that method (key_version=1) cannot be decrypted by the vault and must be migrated via one-time re-encryption to key_version=2. See ADR-020 for the full rationale and migration path.
-- **Cross-references**: ADR-020, [encryption.md](../encryption.md)
+- **Cross-references**: [ADR-020](../decisions/020-hd-derivation-for-encryption-keys.md), [encryption.md](../encryption.md)

docs/architecture/questions/021-remote-vault-administration.md

@@ -6,9 +6,9 @@
 - **Priority**: medium
 - **Resolution**: Remote vault access is **not a feature of the vault crate**. ADR-025 dropped irpc from the vault, making the vault local-only by construction — no `RemoteService` trait, no wire format for vault messages, no default-insecure remote handler. The vault's API is `VaultServiceHandle` (direct method calls), nothing else.
 
-  If remote vault access is ever needed (e.g., the machine→worker pattern), it requires a **separate vault-server crate** that depends on both alknet-core (for `IdentityProvider`, scopes, auth-wrapping) and alknet-vault (for `VaultServiceHandle`). That crate would define its own threat model, access policy, operation filtering (Unlock/Lock local-only), and wire format — and requires its own ADR. This is a deliberate addition, not a flag flip on a default that was already loaded.
+  If remote vault access is ever needed (e.g., the machine→worker pattern), it requires a **separate vault-server crate** that depends on both alknet-core (for `IdentityProvider`, scopes, auth-wrapping) and alkvault (for `VaultServiceHandle`). That crate would define its own threat model, access policy, operation filtering (Unlock/Lock local-only), and wire format — and requires its own ADR. This is a deliberate addition, not a flag flip on a default that was already loaded.
 
   The pre-ADR-025 deferral framed remote access as "non-breaking" (the wire format was additive). That framing was misleading: once workers build dependencies on the remote vault API, disabling it breaks them — the door is operationally one-way even if the wire format is additive. ADR-025 inverts the default: the vault is local-only by construction, and remote access requires building something new, not removing a default.
 
   Per-node vaults are the recommended pattern for multi-node deployments: each node has its own vault and mnemonic; credentials are encrypted *for* the receiving node's public key, not decrypted centrally. This is end-to-end encryption between nodes, matching ADR-008's "capability source" model.
-- **Cross-references**: ADR-005, ADR-008, ADR-014, ADR-018, ADR-019, ADR-025, [protocol.md](../protocol.md), [service.md](../service.md)
+- **Cross-references**: `@alkdev/alknet: ADR-005`, `@alkdev/alknet: ADR-008`, `@alkdev/alknet: ADR-014`, [ADR-018](../decisions/018-vault-standalone-crate.md), [ADR-019](../decisions/019-vault-assembly-layer-only.md), [ADR-025](../decisions/025-vault-local-only-dispatch.md), [protocol.md](../protocol.md), [service.md](../service.md)

docs/architecture/questions/022-key-rotation-mechanism.md

@@ -5,4 +5,4 @@
 - **Door type**: One-way (path scheme), two-way (rotation policy)
 - **Priority**: medium
 - **Resolution**: Key rotation uses version-indexed derivation paths. Each key version maps to a distinct SLIP-0010 path: `m/74'/2'/0'/{version-2}'`. v2 (current) is at `m/74'/2'/0'/0'`; v3 is at `m/74'/2'/0'/1'`; etc. The `decrypt` method derives the key at the path indicated by `encrypted.key_version` (not always at `PATHS::ENCRYPTION`). The `rotate` method decrypts with the old version's key and re-encrypts with the new version's key — no new mnemonic needed. The assembly layer or a migration tool iterates stored blobs and calls `rotate` on each; the vault does not self-rotate. Partial rotation is safe (old keys remain derivable). See ADR-021.
-- **Cross-references**: ADR-020, ADR-021, [encryption.md](../encryption.md), [service.md](../service.md)
+- **Cross-references**: [ADR-020](../decisions/020-hd-derivation-for-encryption-keys.md), [ADR-021](../decisions/021-key-rotation-via-version-indexed-paths.md), [encryption.md](../encryption.md), [service.md](../service.md)