Bump Rust toolchain / MSRV floors to 1.98.1

Workspace-wide sweep to 1.98.1 (rust-toolchain, rust-version, Dockerfile
base images, CI MSRV pins). Docker tags rust:1.98.1, -bookworm and
-slim-bookworm verified to exist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019HnekoM1EidTwQLS3oFVFm

Author: claude

Cargo.toml

@@ -10,7 +10,7 @@ edition = "2021"
 # of the contract crate happens to still succeed today — a coincidence, not a
 # guarantee, and exactly what an untested MSRV declaration buys. Declare what is
 # actually verified.
-rust-version = "1.98"
+rust-version = "1.98.1"
 authors = [
   "Ulrik Sverdrup \"bluss\"",
   "Jim Turner"

crates/encryption/Cargo.toml

@@ -2,7 +2,7 @@
 name = "encryption"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.95"
+rust-version = "1.98.1"
 license = "MIT OR Apache-2.0"
 description = "Zero-knowledge envelope crypto for the Ada stack: Argon2id KDF, XChaCha20-Poly1305 AEAD, Ed25519 signatures, SHA-384 hashing. One codebase for native servers and wasm32 browsers."
 publish = false

crates/fractal/Cargo.toml

@@ -2,7 +2,7 @@
 name = "fractal"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.94"
+rust-version = "1.98.1"
 description = "7+1 phyllotactic SIMD manifold with Euler-gamma singularity correction"
 license = "MIT OR Apache-2.0"
 

crates/p64/Cargo.toml

@@ -2,7 +2,7 @@
 name = "p64"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.94"
+rust-version = "1.98.1"
 description = "Palette64: 64×64 BNN attention matrix from 8 phyllotactic HEEL planes"
 license = "MIT OR Apache-2.0"