feat(functions,bindings): add smart-execute, fast-cli; refactor qalc and rm

- Add _smart_execute: context-aware Ctrl+Enter that routes to qalc when
  the buffer ends with '=', or falls through to standard execute otherwise
- Refactor qalc_eval → _qalc_eval (private helper, same behavior)
- Bind Ctrl+Enter to _smart_execute in all vi modes
- Add fast-cli wrapper (fast.com speed test) and fast placeholder with
  a friendly ANSI redirect message
- Add speedtest-fast abbreviation expanding to fast-cli
- Enhance _replace_command_token to handle sudo-prefixed commands: places
  cursor at index 5 (between sudo and the replacement slot)
- Improve rm error reporting: colored output, culprit-path listing, and
  cleaned technical detail for non-missing-file errors
- Add SPDX copyright headers to cat, ld, claude-docs, claude-pr functions
- Update README: Ctrl+Enter binding, fast-cli/fast functions, speedtest-fast abbr

functions/ld.fish

@@ -1,6 +1,7 @@
 # Copyright (C) 2026 Rootiest
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
+# Run lazydocker on the current Docker context
 function ld --description 'Run lazydocker on the current Docker context'
     # Fetch the host endpoint of the currently active Docker context
     set -l current_host (docker context inspect --format '{{.Endpoints.docker.Host}}')