refactor: apply minimal tfcode branding

- Rename packages/opencode → packages/tfcode (directory only)
- Rename bin/opencode → bin/tfcode (CLI binary)
- Rename .opencode → .tfcode (config directory)
- Update package.json name and bin field
- Update config directory path references (.tfcode)
- Keep internal code references as 'opencode' for easy upstream sync
- Keep @opencode-ai/* workspace package names

This minimal branding approach allows clean merges from upstream
opencode repository while providing tfcode branding for users.

.tfcode/command/ai-deps.md

@@ -0,0 +1,24 @@
+---
+description: "Bump AI sdk dependencies minor / patch versions only"
+---
+
+Please read @package.json and @packages/opencode/package.json.
+
+Your job is to look into AI SDK dependencies, figure out if they have versions that can be upgraded (minor or patch versions ONLY no major ignore major changes).
+
+I want a report of every dependency and the version that can be upgraded to.
+What would be even better is if you can give me brief summary of the changes for each dep and a link to the changelog for each dependency, or at least some reference info so I can see what bugs were fixed or new features were added.
+
+Consider using subagents for each dep to save your context window.
+
+Here is a short list of some deps (please be comprehensive tho):
+
+- "ai"
+- "@ai-sdk/openai"
+- "@ai-sdk/anthropic"
+- "@openrouter/ai-sdk-provider"
+- etc, etc
+
+DO NOT upgrade the dependencies yet, just make a list of all dependencies and their versions that can be upgraded to minor or patch versions only.
+
+Write up your findings to ai-sdk-updates.md