Remove generated integration files, add to .gitignore

The 250+ generated files in integrations/ were adding repo bloat and would
cause merge conflicts when agents change. Run scripts/convert.sh to
regenerate them locally.

What's committed:
- scripts/convert.sh and scripts/install.sh (the actual value)
- integrations/*/README.md (docs for each tool)
- integrations/README.md (overview)
- .gitignore updated to exclude all generated output dirs

What's excluded (add to .gitignore):
- integrations/antigravity/agency-*/
- integrations/gemini-cli/skills/ + gemini-extension.json
- integrations/opencode/agent/
- integrations/cursor/rules/
- integrations/aider/CONVENTIONS.md
- integrations/windsurf/.windsurfrules

.gitignore

@@ -62,3 +62,14 @@ scratch/
 notes/
 TODO.md
 NOTES.md
+
+# Generated integration files — run scripts/convert.sh to regenerate locally
+# The scripts/ and integrations/*/README.md files ARE committed; only generated
+# agent/skill files are excluded.
+integrations/antigravity/agency-*/
+integrations/gemini-cli/skills/
+integrations/gemini-cli/gemini-extension.json
+integrations/opencode/agent/
+integrations/cursor/rules/
+integrations/aider/CONVENTIONS.md
+integrations/windsurf/.windsurfrules