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/doctor/constants.ts

@@ -1,4 +1,5 @@
 import color from "picocolors"
+import { PLUGIN_NAME } from "../../shared"
 
 export const SYMBOLS = {
   check: color.green("\u2713"),
@@ -38,6 +39,6 @@ export const EXIT_CODES = {
 
 export const MIN_OPENCODE_VERSION = "1.0.150"
 
-export const PACKAGE_NAME = "oh-my-opencode"
+export const PACKAGE_NAME = PLUGIN_NAME
 
 export const OPENCODE_BINARIES = ["opencode", "opencode-desktop"] as const