Add bridge launch overrides for tests and bump Pi runtime to v0.1.4

[mmprotest]

Motivation

• Extension tests on Windows failed with spawn EFTYPE because tests passed a fake bridge path that is not directly executable on Node's spawn without using shell:true.
• The runtime release moved from 0.1.3 to 0.1.4 and tests/docs needed to reflect the new runtime version.
• Ensure tests can run fake bridge scripts via process.execPath while keeping production bridge launch semantics unchanged.

Description

• Added BridgeLaunchOptions (fields executableOverride?: string and bridgeArgsOverride?: string[]) and threaded them into BridgeProcessOptions so launches may override the executable and args (file: integrations/pi-villani/src/process.ts).
• Made VillaniBridgeProcess use the launch overrides when present, while preserving production defaults of spawn(executable, ['bridge','--stdio'], { shell: false, ... }) (file: integrations/pi-villani/src/process.ts).
• Threaded bridgeLaunchOptions through assertBridgePing() and runVillani() and added a helper bridgeLaunchOptions(ctx) to read overrides from ctx (file: integrations/pi-villani/src/index.ts).
• Updated extension tests to call bridgePing() and runVillani() with bridgeLaunchOptions: { executableOverride: process.execPath, bridgeArgsOverride: [fakeScript] } so fake bridge scripts are launched as node fakeScript (file: integrations/pi-villani/src/extension.test.ts).
• Bumped Pi runtime version constant to 0.1.4 and updated README/docs to reference v0.1.4 so version consistency tests derive expected names from VILLANI_RUNTIME_VERSION (file: integrations/pi-villani/src/runtimeConfig.ts, README.md, docs/release.md).
• No changes were made to runner behaviour, model proxy behaviour, bridge protocol semantics, or UI copy.

Testing

• Ran cd integrations/pi-villani && npm run build which compiles TypeScript successfully.
• Ran cd integrations/pi-villani && npm test which executed the test suite (91 tests) and all tests passed (# pass 91 # fail 0).
• Ran cd integrations/pi-villani && npm pack --dry-run which produced a pack listing for @mmprotest/pi-villani@0.1.4 successfully.

---

Codex Task