feat: add --notes flag to bd create command (GH#830)

Add --notes flag to bd create command, enabling agents to set notes
during issue creation instead of requiring a separate update command.

Motivation: AI agents repeatedly tried to use --notes with bd create.
Context is fresh at creation time - forcing a two-step process means
context loss or workflow interruption.

Changes:
- cmd/bd/flags.go: Added --notes flag to common issue flags
- cmd/bd/create.go: Read and pass notes in both RPC and direct modes
- cmd/bd/update.go: Removed duplicate --notes flag definition
- internal/rpc/protocol.go: Added Notes field to CreateArgs
- internal/rpc/server_issues_epics.go: Process Notes in handleCreate
- cmd/bd/create_notes_test.go: Comprehensive test coverage
- website/docs/cli-reference/issues.md: Documentation

Also adds gitignore entries for Augment AI and .beads/redirect.

Co-authored-by: Leon Letto <lettol@vmware.com>

.beads/.gitignore

@@ -19,6 +19,10 @@ sync-state.json
 db.sqlite
 bd.db
 
+# Worktree redirect file (contains relative path to main repo's .beads/)
+# Must not be committed as paths would be wrong in other clones
+redirect
+
 # Merge artifacts (temporary files from 3-way merge)
 beads.base.jsonl
 beads.base.meta.json