feat: add OPENCODE_DISABLE_PROJECT_DISCOVERY env var

[kdcokenny]

Closes #7559

Adds environment variable to disable project-level config discovery for external tooling integration.

Changes

• Skip project config files when flag is set
• Skip project .opencode/ directories
• Skip local rule files (AGENTS.md, CLAUDE.md, CONTEXT.md)
• Relative instructions without OPENCODE_CONFIG_DIR log warning and skip
• Use dynamic getters for env var flags (fixes runtime evaluation)

Usage

OPENCODE_DISABLE_PROJECT_DISCOVERY=true \
OPENCODE_CONFIG_DIR=/path/to/profile/ \
opencode

Verification

Automated

Test	Command	Result
Unit tests	bun test --filter "OPENCODE_DISABLE_PROJECT_DISCOVERY"	5/5 passing

Manual

Setup:

mkdir -p /tmp/test-proj
cat > /tmp/test-proj/opencode.json << 'EOF'
{"mcp": {"test_server_1": {"type": "remote", "url": "https://example.com", "enabled": true}}}
EOF
echo "Always say PINEAPPLE first." > /tmp/test-proj/AGENTS.md

Test	Command	Expected	Result
Config without flag	bun dev /tmp/test-proj run "what tools do you have?"	Shows test_server_1	✅
Config with flag	OPENCODE_DISABLE_PROJECT_DISCOVERY=true bun dev /tmp/test-proj run "what tools do you have?"	No test_server_1	✅
AGENTS.md without flag	bun dev /tmp/test-proj run "say hello"	Says PINEAPPLE	✅
AGENTS.md with flag	OPENCODE_DISABLE_PROJECT_DISCOVERY=true bun dev /tmp/test-proj run "say hello"	No PINEAPPLE	✅
Global config preserved	OPENCODE_DISABLE_PROJECT_DISCOVERY=true bun dev /tmp/test-proj run "what tools do you have?"	Shows global MCP servers	✅

Cleanup:

rm -rf /tmp/test-proj