Consolidate duplicate patterns and simplify codebase (#1317)

* refactor(shared): unify binary downloader and session path storage

- Create binary-downloader.ts for common download/extract logic
- Create session-injected-paths.ts for unified path tracking
- Refactor comment-checker, ast-grep, grep downloaders to use shared util
- Consolidate directory injector types into shared module

* feat(shared): implement unified model resolution pipeline

- Create ModelResolutionPipeline for centralized model selection
- Refactor model-resolver to use pipeline
- Update delegate-task and config-handler to use unified logic
- Ensure consistent model resolution across all agent types

* refactor(agents): simplify agent utils and metadata management

- Extract helper functions for config merging and env context
- Register prompt metadata for all agents
- Simplify agent variant detection logic

* cleanup: inline utilities and remove unused exports

- Remove case-insensitive.ts (inline with native JS)
- Simplify opencode-version helpers
- Remove unused getModelLimit, createCompactionContextInjector exports
- Inline transcript entry creation in claude-code-hooks
- Update tests accordingly

---------

Co-authored-by: justsisyphus <justsisyphus@users.noreply.github.com>

src/shared/index.ts

@@ -20,6 +20,7 @@ export * from "./opencode-version"
 export * from "./permission-compat"
 export * from "./external-plugin-detector"
 export * from "./zip-extractor"
+export * from "./binary-downloader"
 export * from "./agent-variant"
 export * from "./session-cursor"
 export * from "./shell-env"
@@ -27,9 +28,14 @@ export * from "./system-directive"
 export * from "./agent-tool-restrictions"
 export * from "./model-requirements"
 export * from "./model-resolver"
+export {
+  resolveModelPipeline,
+  type ModelResolutionRequest,
+  type ModelResolutionResult as ModelResolutionPipelineResult,
+  type ModelResolutionProvenance,
+} from "./model-resolution-pipeline"
 export * from "./model-availability"
 export * from "./connected-providers-cache"
-export * from "./case-insensitive"
 export * from "./session-utils"
 export * from "./tmux"
 export * from "./model-suggestion-retry"