Patch support for extensions

[algonixdev]

Some extensions occasionally need a small local fix that isn't merged upstream yet (a bug, a compatibility issue...). Until now the only option was to fork the extension. This PR adds a patch mechanism that's applied automatically on every install/update, without maintaining a fork.

Changes

• entrypoint.sh: new patch_extension function, called from install_extension on every install/update (fresh clone or git reset --hard → upstream code is always "clean", so the patch must be reapplied every time). Applies all .patch files found in patches// in lexical order, idempotently (skips if already applied, via git apply --check --reverse), no-op if the patches// directory doesn't exist.
• patches/README.md: documents the format and the patch-creation workflow (git diff > patches//001-description.patch).
• patches/_example/: a fictitious example illustrating the convention (never applied — no extension is named _example).
• patches/comfyui-ollama/001-fix-context-keyerror.patch: first real patch — fixes a KeyError on response['context'] by switching to response.get('context', []).
• Dockerfile: copies the patches/ directory into the image.
• AGENTS.md: new "Patching an extension" section documenting the convention for future contributions.

[bigbrozer]

It looks good for me and I like the idea. Will merge for next release. Thank you for this proposal <3