fix(docs): correct bd dep add syntax and semantics

Fixed incorrect bd dep documentation in prime.go, cursor.go, and aider.go

- Added missing 'add' subcommand (was 'bd dep <from> <to>', now 'bd dep add <issue> <depends-on>')
- Corrected semantics (docs claimed 'from blocks to' but actual behavior is 'issue depends on depends-on')

This fixes AI agents and users consistently creating dependencies in the wrong direction.

Co-authored-by: jflam <jflam@users.noreply.github.com>

cmd/bd/prime.go

@@ -227,7 +227,7 @@ bd sync            # Push to remote
 - ` + "`bd close <id> --reason=\"explanation\"`" + ` - Close with reason
 
 ### Dependencies & Blocking
-- ` + "`bd dep <from> <to>`" + ` - Add blocker dependency (from blocks to)
+- ` + "`bd dep add <issue> <depends-on>`" + ` - Add dependency (issue depends on depends-on)
 - ` + "`bd blocked`" + ` - Show all blocked issues
 - ` + "`bd show <id>`" + ` - See what's blocking/blocked by this issue
 
@@ -252,7 +252,7 @@ bd update <id> --status=in_progress  # Claim it
 ` + "```bash" + `
 bd create --title="Implement feature X" --type=feature
 bd create --title="Write tests for X" --type=task
-bd dep beads-xxx beads-yyy  # Feature blocks tests
+bd dep add beads-yyy beads-xxx  # Tests depend on Feature (Feature blocks tests)
 ` + "```" + `
 `
 	fmt.Print(context)