fix(ci): resolve all test failures + complete rename compat layer

Sisyphus-authored fixes across 15 files:

- plugin-identity: align CONFIG_BASENAME with actual config file name
- add-plugin-to-opencode-config: handle legacy→canonical name migration
- plugin-detection tests: update expectations for new identity constants
- doctor/system: fix legacy name warning test assertions
- install tests: align with new plugin name
- chat-params tests: fix mock isolation
- model-capabilities tests: fix snapshot expectations
- image-converter: fix platform-dependent test assertions (Linux CI)
- example configs: expanded with more detailed comments

Full suite: 4484 pass, 0 fail, typecheck clean.

src/cli/install.test.ts

@@ -113,10 +113,10 @@ describe("install CLI - binary check behavior", () => {
     const configPath = join(tempDir, "opencode.json")
     expect(existsSync(configPath)).toBe(true)
 
-    // then opencode.json should have plugin entry
     const config = JSON.parse(readFileSync(configPath, "utf-8"))
     expect(config.plugin).toBeDefined()
-    expect(config.plugin.some((p: string) => p.includes("oh-my-opencode"))).toBe(true)
+    expect(config.plugin.some((p: string) => p.includes("oh-my-openagent"))).toBe(true)
+    expect(config.plugin.some((p: string) => p.includes("oh-my-opencode"))).toBe(false)
 
     // then exit code should be 0 (success)
     expect(exitCode).toBe(0)