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/opencode-version.test.ts

@@ -2,8 +2,6 @@ import { describe, test, expect, beforeEach, afterEach } from "bun:test"
 import {
   parseVersion,
   compareVersions,
-  isVersionGte,
-  isVersionLt,
   getOpenCodeVersion,
   isOpenCodeVersionAtLeast,
   resetVersionCache,
@@ -103,32 +101,6 @@ describe("opencode-version", () => {
     })
   })
 
-  describe("isVersionGte", () => {
-    test("returns true when a >= b", () => {
-      expect(isVersionGte("1.1.1", "1.1.1")).toBe(true)
-      expect(isVersionGte("1.1.2", "1.1.1")).toBe(true)
-      expect(isVersionGte("1.2.0", "1.1.1")).toBe(true)
-      expect(isVersionGte("2.0.0", "1.1.1")).toBe(true)
-    })
-
-    test("returns false when a < b", () => {
-      expect(isVersionGte("1.1.0", "1.1.1")).toBe(false)
-      expect(isVersionGte("1.0.9", "1.1.1")).toBe(false)
-      expect(isVersionGte("0.9.9", "1.1.1")).toBe(false)
-    })
-  })
-
-  describe("isVersionLt", () => {
-    test("returns true when a < b", () => {
-      expect(isVersionLt("1.1.0", "1.1.1")).toBe(true)
-      expect(isVersionLt("1.0.150", "1.1.1")).toBe(true)
-    })
-
-    test("returns false when a >= b", () => {
-      expect(isVersionLt("1.1.1", "1.1.1")).toBe(false)
-      expect(isVersionLt("1.1.2", "1.1.1")).toBe(false)
-    })
-  })
 
   describe("getOpenCodeVersion", () => {
     beforeEach(() => {