Refresh workshop content for current Copilot CLI behavior

[jsburckhardt]

Revalidates all 13 workshop modules, all 13 slide decks, and the landing page against the installed Copilot CLI, and bumps VALIDATED_CLI_VERSION from 1.0.69-1 to 1.0.79-5.

An accuracy audit compared every documented command, path, flag, config key, and schema against the running CLI. It found 21 confirmed inaccuracies and 14 undocumented capabilities. All were applied, then four validators (cross-reference, slide-sync, exercise-lint, landing-page) audited the result and their findings were fixed too.

Exercises that were broken

Problem	Effect on a participant
Custom agents documented at ~/.config/copilot/agents/	Wrong path. Module 8 Exercise 5 produced an agent that was never loaded. Fixed to ~/.copilot/agents/ (11 occurrences).
Folder trust requirement for repository hooks undocumented	Every hooks exercise silently produced nothing, with no error to debug. Verified empirically that personal hooks in ~/.copilot/hooks/ fire regardless of trust.
Six nested code fences in module 8 terminated early	Four cat > ... << 'EOF' heredocs were truncated, so learners wrote incomplete .agent.md files. All five heredocs now execute end to end.
lsp.json schema was fabricated	Replaced with the real ~/.copilot/lsp-config.json; fileExtensions is a map of extension to language ID, not an array.
COPILOT_DEBUG, ~/.copilot/sessions/, ~/.copilot/auth*	None exist. Session data lives under ~/.copilot/session-state/.
configure-copilot sub-agent, "Critic Agent", /limits predict	None exist. Removed.
copilot plugin update with no argument	Fails. Now documents an argument or --all.
/theme show|set|list	No such subcommands. Theme is set via /settings theme <value>.
/undo and /rewind taught as two commands	They are one aliased command.

Security

Exercises previously instructed participants to print ~/.copilot/config.json, which holds a live auth token — a real risk in a screen-shared workshop. Those steps are replaced with a key-scoped read, user settings are pointed at ~/.copilot/settings.json, and warnings were added to modules 04, 08, 10, 12 and 13.

Rebuilt from the live CLI

Built-in tools, agents and skills tables · all 15 hook events and the two mutually exclusive payload shapes · settings keys, environment variables, startup flags and help topics · command sandboxing, session limits and AI credits, the copilot plugins family, and the /mcp, /session and /permissions subcommands.

Also fixes invalid GitHub Actions YAML, Python and JavaScript samples, splits mixed shell/slash-command fences so they are safe to copy-paste, and moves the closing slide from deck 12 to deck 13 (it previously told the room the workshop was over one module early).

Validation

Check	Result
Cross-reference (links, anchors, structure, agent maps)	0 issues
Exercise lint (bash, JSON, numbering, references)	0 issues
Slide sync across 13 decks	0 desyncs
Fence balance / table integrity across 27 files	0 issues
JSON samples	34/34 parse
Heredocs	30/30 parse
Marp render	13/13 decks

Documentation remains versionless per the repo convention; the only version references are the deliberate VALIDATED_CLI_VERSION stamp and its derived README badge and landing-page stat.

The second commit is unrelated devcontainer work: building from a Dockerfile so registry endpoints can be injected at build time, a lock file pinning features to digests, and the copilot-persistence, tmux and glow features.