feat(daemon): unify auto-sync config for simpler agent workflows (#904)

* feat(daemon): unify auto-sync config for simpler agent workflows

## Problem

Agents running `bd sync` at session end caused delays in the Claude Code
"event loop", slowing development. The daemon was already auto-exporting
DB→JSONL instantly, but auto-commit and auto-push weren't enabled by
default when sync-branch was configured - requiring manual `bd sync`.

Additionally, having three separate config options (auto-commit, auto-push,
auto-pull) was confusing and could get out of sync.

## Solution

Simplify to two intuitive sync modes:

1. **Read/Write Mode** (`daemon.auto-sync: true` or `BEADS_AUTO_SYNC=true`)
   - Enables auto-commit + auto-push + auto-pull
   - Full bidirectional sync - eliminates need for manual `bd sync`
   - Default when sync-branch is configured

2. **Read-Only Mode** (`daemon.auto-pull: true` or `BEADS_AUTO_PULL=true`)
   - Only receives updates from team
   - Does NOT auto-publish changes
   - Useful for experimental work or manual review before sharing

## Benefits

- **Faster agent workflows**: No more `bd sync` delays at session end
- **Simpler config**: Two modes instead of three separate toggles
- **Backward compatible**: Legacy auto_commit/auto_push settings still work
  (treated as auto-sync=true)
- **Adaptive `bd prime`**: Session close protocol adapts when daemon is
  auto-syncing (shows simplified 4-step git workflow, no `bd sync`)
- **Doctor warnings**: `bd doctor` warns about deprecated legacy config

## Changes

- cmd/bd/daemon.go: Add loadDaemonAutoSettings() with unified config logic
- cmd/bd/doctor.go: Add CheckLegacyDaemonConfig call
- cmd/bd/doctor/daemon.go: Add CheckDaemonAutoSync, CheckLegacyDaemonConfig
- cmd/bd/init_team.go: Use daemon.auto-sync in team wizard
- cmd/bd/prime.go: Detect daemon auto-sync, adapt session close protocol
- cmd/bd/prime_test.go: Add stubIsDaemonAutoSyncing for testing

* docs: add comprehensive daemon technical analysis

Add daemon-summary.md documenting the beads daemon architecture,
memory analysis (explaining the 30-35MB footprint), platform support
comparison, historical problems and fixes, and architectural guidance
for other projects implementing similar daemon patterns.

Key sections:
- Architecture deep dive with component diagrams
- Memory breakdown (SQLite WASM runtime is the main contributor)
- Platform support matrix (macOS/Linux full, Windows partial)
- Historical bugs and their fixes with reusable patterns
- Analysis of daemon usefulness without database (verdict: low value)
- Expert-reviewed improvement proposals (3 recommended, 3 skipped)
- Technical design patterns for other implementations

* feat: add cross-platform CI matrix and dual-mode test framework

Cross-Platform CI:
- Add Windows, macOS, Linux matrix to catch platform-specific bugs
- Linux: full tests with race detector and coverage
- macOS: full tests with race detector
- Windows: full tests without race detector (performance)
- Catches bugs like GH#880 (macOS path casing) and GH#387 (Windows daemon)

Dual-Mode Test Framework (cmd/bd/dual_mode_test.go):
- Runs tests in both direct mode and daemon mode
- Prevents recurring bug pattern (GH#719, GH#751, bd-fu83)
- Provides DualModeTestEnv with helper methods for common operations
- Includes 5 example tests demonstrating the pattern

Documentation:
- Add dual-mode testing section to CONTRIBUTING.md
- Document RunDualModeTest API and available helpers

Test Fixes:
- Fix sync_local_only_test.go gitPull/gitPush calls
- Add gate_no_daemon_test.go for beads-70c4 investigation

* fix(test): isolate TestFindBeadsDir tests with BEADS_DIR env var

The tests were finding the real project's .beads directory instead of
the temp directory because FindBeadsDir() walks up the directory tree.
Using BEADS_DIR env var provides proper test isolation.

* fix(test): stop daemon before running test suite guard

The test suite guard checks that tests don't modify the real repo's .beads
directory. However, a background daemon running auto-sync would touch
issues.jsonl during test execution, causing false positives.

Changes:
- Set BEADS_NO_DAEMON=1 to prevent daemon auto-start from tests
- Stop any running daemon for the repo before taking the "before" snapshot
- Uses exec to call `bd daemon --stop` to avoid import cycle issues

* chore: revert .beads/issues.jsonl to upstream/main

Per CONTRIBUTING.md, .beads/issues.jsonl should not be modified in PRs.

cmd/bd/sync_local_only_test.go

@@ -19,15 +19,15 @@ func TestLocalOnlyMode(t *testing.T) {
 
 	// Create temp directory for local-only repo
 	tempDir := t.TempDir()
-	
+
 	// Initialize local git repo without remote
 	runGitCmd(t, tempDir, "init")
 	runGitCmd(t, tempDir, "config", "user.email", "test@example.com")
 	runGitCmd(t, tempDir, "config", "user.name", "Test User")
-	
+
 	// Change to temp directory so git commands run in the test repo
 	t.Chdir(tempDir)
-	
+
 	// Verify no remote exists
 	cmd := exec.Command("git", "remote")
 	output, err := cmd.Output()
@@ -39,19 +39,19 @@ func TestLocalOnlyMode(t *testing.T) {
 	}
 
 	ctx := context.Background()
-	
+
 	// Test hasGitRemote returns false
 	if hasGitRemote(ctx) {
 		t.Error("Expected hasGitRemote to return false for local-only repo")
 	}
 
 	// Test gitPull returns nil (no error)
-	if err := gitPull(ctx); err != nil {
+	if err := gitPull(ctx, ""); err != nil {
 		t.Errorf("gitPull should gracefully skip when no remote, got error: %v", err)
 	}
 
 	// Test gitPush returns nil (no error)
-	if err := gitPush(ctx); err != nil {
+	if err := gitPush(ctx, ""); err != nil {
 		t.Errorf("gitPush should gracefully skip when no remote, got error: %v", err)
 	}
 
@@ -60,7 +60,7 @@ func TestLocalOnlyMode(t *testing.T) {
 	if err := os.MkdirAll(beadsDir, 0750); err != nil {
 		t.Fatalf("Failed to create .beads dir: %v", err)
 	}
-	
+
 	jsonlPath := filepath.Join(beadsDir, "issues.jsonl")
 	if err := os.WriteFile(jsonlPath, []byte(`{"id":"test-1","title":"Test"}`+"\n"), 0644); err != nil {
 		t.Fatalf("Failed to write JSONL: %v", err)
@@ -102,7 +102,7 @@ func TestWithRemote(t *testing.T) {
 
 	// Clone it
 	runGitCmd(t, tempDir, "clone", remoteDir, cloneDir)
-	
+
 	// Change to clone directory
 	t.Chdir(cloneDir)
 
@@ -116,5 +116,5 @@ func TestWithRemote(t *testing.T) {
 	// Verify git pull doesn't error (even with empty remote)
 	// Note: pull might fail with "couldn't find remote ref", but that's different
 	// from the fatal "'origin' does not appear to be a git repository" error
-	gitPull(ctx) // Just verify it doesn't panic
+	_ = gitPull(ctx, "") // Just verify it doesn't panic
 }