fix: prefer .js over .ts when loading plugins for npm compatibility

[simongdavies]

• Add resolvePluginSource() helper (prefers .ts in dev, .js under node_modules)
• Fix schema extraction to prefer .ts source for Rust parser
• Fix fast-path plugin enable to call loadSource() before enabling
• Root cause: schema extraction failed on compiled .js, config keys unrecognised, allowedDomains never set

[Copilot]

Pull request overview

This PR improves plugin loading behavior to be compatible with npm-installed layouts by centralizing “which file to read/import” decisions (.ts vs .js), and adjusts schema extraction and the approved fast-path to avoid misconfigurations (e.g., missing allowedDomains due to schema extraction failures).

Changes:

• Add resolvePluginSource() and use it for plugin source reads/imports and approval hashing.
• Update schema extraction to prefer .ts when available, with fallbacks for node_modules/runtime contexts.
• Ensure approved fast-path loads plugin source before enabling; add targeted tests for resolution behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
tests/plugin-manager.test.ts	Adds unit tests covering .ts vs .js resolution rules for dev vs node_modules.
src/plugin-system/manager.ts	Introduces resolvePluginSource(), updates hashing/source loading, and adjusts schema extraction + verification path usage.
src/agent/slash-commands.ts	Loads plugin source before enabling in the approved fast-path to support subsequent hash verification.
src/agent/index.ts	Uses resolvePluginSource() when dynamically importing enabled plugins into the sandbox.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.