chore(licence): migrate Cargo.toml license field from PMPL-1.0 to MPL-2.0

Closes part of Item 2 of the 2026-05-26 estate tech-debt audit
follow-up (hyperpolymath/standards#196).

The estate-wide policy is 'MPL-1.0/PMPL-1.0 -> MPL-2.0' (see
estate language policy memory). This PR migrates the manifest's
declared license field; the LICENSE file's Palimpsest preamble (if
present) is unchanged, and the MPL-2.0 body text it wraps is the
load-bearing licence.

The licence-consistency CI check landed in standards#201 catches
future SPDX-vs-manifest drift.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

Cargo.toml

@@ -3,7 +3,7 @@ name = "mobile-ai-orchestrator"
 version = "1.0.0"
 edition = "2021"
 authors = ["Jonathan Bowman <hyperpolymath@protonmail.com>"]
-license = "PMPL-1.0"
+license = "MPL-2.0"
 repository = "https://github.com/Hyperpolymath/heterogenous-mobile-computing"
 description = "Hybrid AI orchestration system for constrained mobile platforms with reservoir computing"
 keywords = ["ai", "mobile", "orchestration", "reservoir-computing", "offline-first"]