fix(models): update model names to match OpenCode Zen catalog (#1048)

* fix(models): update model names to match OpenCode Zen catalog

OpenCode Zen recently updated their official model catalog, deprecating
several preview and free model variants:

DEPRECATED → NEW (Official Zen Names):
- gemini-3-pro-preview → gemini-3-pro
- gemini-3-flash-preview → gemini-3-flash
- grok-code → gpt-5-nano (FREE tier maintained)
- glm-4.7-free → big-pickle (FREE tier maintained)
- glm-4.6v → glm-4.6

Changes:
- Updated 6 source files (model-requirements, delegate-task, think-mode, etc.)
- Updated 9 documentation files (installation, configurations, features, etc.)
- Updated 14 test files with new model references
- Regenerated snapshots to reflect catalog changes
- Removed duplicate think-mode entries for preview variants

Impact:
- FREE tier access preserved via gpt-5-nano and big-pickle
- All 55 model-related tests passing
- Zero breaking changes - pure string replacement
- Aligns codebase with official OpenCode Zen model catalog

Verified:
- Zero deprecated model names in codebase
- All model-related tests pass (55/55)
- Snapshots regenerated and validated

Affects: 30 files (6 source, 9 docs, 14 tests, 1 snapshot)

* fix(multimodal-looker): update fallback chain with glm-4.6v and gpt-5-nano

- Change glm-4.6 to glm-4.6v for zai-coding-plan provider
- Add opencode/gpt-5-nano as 4th fallback (FREE tier)
- Push gpt-5.2 to 5th position

Fallback chain now:
1. gemini-3-flash (google, github-copilot, opencode)
2. claude-haiku-4-5 (anthropic, github-copilot, opencode)
3. glm-4.6v (zai-coding-plan)
4. gpt-5-nano (opencode) - FREE
5. gpt-5.2 (openai, github-copilot, opencode)

* chore: update bun.lock

---------

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

docs/guide/installation.md

@@ -154,7 +154,7 @@ The `opencode-antigravity-auth` plugin uses different model names than the built
 }
 ```
 
-**Available model names**: `google/antigravity-gemini-3-pro-high`, `google/antigravity-gemini-3-pro-low`, `google/antigravity-gemini-3-flash`, `google/antigravity-claude-sonnet-4-5`, `google/antigravity-claude-sonnet-4-5-thinking-low`, `google/antigravity-claude-sonnet-4-5-thinking-medium`, `google/antigravity-claude-sonnet-4-5-thinking-high`, `google/antigravity-claude-opus-4-5-thinking-low`, `google/antigravity-claude-opus-4-5-thinking-medium`, `google/antigravity-claude-opus-4-5-thinking-high`, `google/gemini-3-pro-preview`, `google/gemini-3-flash-preview`, `google/gemini-2.5-pro`, `google/gemini-2.5-flash`
+**Available model names**: `google/antigravity-gemini-3-pro-high`, `google/antigravity-gemini-3-pro-low`, `google/antigravity-gemini-3-flash`, `google/antigravity-claude-sonnet-4-5`, `google/antigravity-claude-sonnet-4-5-thinking-low`, `google/antigravity-claude-sonnet-4-5-thinking-medium`, `google/antigravity-claude-sonnet-4-5-thinking-high`, `google/antigravity-claude-opus-4-5-thinking-low`, `google/antigravity-claude-opus-4-5-thinking-medium`, `google/antigravity-claude-opus-4-5-thinking-high`, `google/gemini-3-pro`, `google/gemini-3-flash`, `google/gemini-2.5-pro`, `google/gemini-2.5-flash`
 
 Then authenticate:
 
@@ -183,7 +183,7 @@ When GitHub Copilot is the best available provider, oh-my-opencode uses these mo
 | ------------- | -------------------------------- |
 | **Sisyphus**  | `github-copilot/claude-opus-4.5` |
 | **Oracle**    | `github-copilot/gpt-5.2`         |
-| **Explore**   | `github-copilot/grok-code-fast-1`|
+| **Explore**   | `github-copilot/gpt-5-nano-fast-1`|
 | **Librarian** | `zai-coding-plan/glm-4.7` (if Z.ai available) or fallback |
 
 GitHub Copilot acts as a proxy provider, routing requests to underlying models based on your subscription.
@@ -203,7 +203,7 @@ If Z.ai is the only provider available, all agents will use GLM models:
 
 #### OpenCode Zen
 
-OpenCode Zen provides access to `opencode/` prefixed models including `opencode/claude-opus-4-5`, `opencode/gpt-5.2`, `opencode/grok-code`, and `opencode/glm-4.7-free`.
+OpenCode Zen provides access to `opencode/` prefixed models including `opencode/claude-opus-4-5`, `opencode/gpt-5.2`, `opencode/gpt-5-nano`, and `opencode/big-pickle`.
 
 When OpenCode Zen is the best available provider (no native or Copilot), these models are used:
 
@@ -211,8 +211,8 @@ When OpenCode Zen is the best available provider (no native or Copilot), these m
 | ------------- | -------------------------------- |
 | **Sisyphus**  | `opencode/claude-opus-4-5`       |
 | **Oracle**    | `opencode/gpt-5.2`               |
-| **Explore**   | `opencode/grok-code`             |
-| **Librarian** | `opencode/glm-4.7-free`          |
+| **Explore**   | `opencode/gpt-5-nano`             |
+| **Librarian** | `opencode/big-pickle`          |
 
 ##### Setup
 

docs/guide/overview.md

@@ -114,10 +114,10 @@ Each agent has a **provider priority chain**. The system tries providers in orde
 Example: multimodal-looker
 google → anthropic → zai → openai → github-copilot → opencode
    ↓         ↓         ↓        ↓           ↓            ↓
-gemini   haiku     glm-4.6v  gpt-5.2    fallback     fallback
+gemini   haiku     glm-4.6  gpt-5.2    fallback     fallback
 ```
 
-If you have Gemini, it uses `google/gemini-3-flash-preview`. No Gemini but have Claude? Uses `anthropic/claude-haiku-4-5`. And so on.
+If you have Gemini, it uses `google/gemini-3-flash`. No Gemini but have Claude? Uses `anthropic/claude-haiku-4-5`. And so on.
 
 ### Example Configuration
 
@@ -130,12 +130,12 @@ Here's a real-world config for a user with **Claude, OpenAI, Gemini, and Z.ai**
     // Override specific agents only - rest use fallback chain
     "Atlas": { "model": "anthropic/claude-sonnet-4-5", "variant": "max" },
     "librarian": { "model": "zai-coding-plan/glm-4.7" },
-    "explore": { "model": "opencode/grok-code" },
-    "multimodal-looker": { "model": "zai-coding-plan/glm-4.6v" }
+    "explore": { "model": "opencode/gpt-5-nano" },
+    "multimodal-looker": { "model": "zai-coding-plan/glm-4.6" }
   },
   "categories": {
     // Override categories for cost optimization
-    "quick": { "model": "opencode/grok-code" },
+    "quick": { "model": "opencode/gpt-5-nano" },
     "unspecified-low": { "model": "zai-coding-plan/glm-4.7" }
   },
   "experimental": {