docs: refresh workshop content for current Copilot CLI behavior

[jsburckhardt]

Refreshes all 13 workshop modules and slide decks against the currently installed CLI. Every claim below was verified against live CLI output, and every module was then executed end-to-end in the workshop Docker container.

Accuracy corrections

Fix	Modules
sandbox.gitAuth/ghAuth → sandbox.auth.git/auth.gh — wrong key was silently ignored	04, 13
--share/--share-gist are non-interactive-only; /share for live sessions	11, 12, 13
Split --resume (session picker) from --continue (most recent session)	11, 12
shell(git) → shell(git:*) — bare form never matched git subcommands	02, 12
--available-tools/--excluded-tools take tool names, not permission rule kinds	12
/usage reports AI credits, not premium requests	10
/plugins → /plugin; --scope gains session, working-directory	06, 07
Added third built-in skill discover-resources	06
copilot mcp list omits built-in servers; /mcp shows them	05
assisted mode requires experimental auto-approval	04
/sandbox also registers under a managed policy	04
Inline hook locations: global config.json vs repo settings.json	09
Eight off-by-one module prerequisite references	03–10, 13

Coverage added

• Flags: --sandbox, --assisted-approval, --usage-output-file, --enable-mcp-server, --extension-sdk-path, --no-eager-powershell-resolution, --remote, --remote-export
• Settings: bannerStyle, defaultMode, defaultPermissionMode
• Env vars: COPILOT_ASSISTED_APPROVAL, COPILOT_MULTIPLEXER, COPILOT_INLINE_IMAGES_HERDR
• Commands: copilot app, copilot init, /exit print, /model sub-options
• Added jq and gh to prerequisites

Exercise bugs found by actually running the workshop

These all passed a syntax check but broke or misbehaved when executed:

• A > [!TIP] callout was trapped inside a << 'EOF' heredoc, so it was written verbatim into the instructions file the reader generates
• Three bash fences contained blocking interactive sessions and in-session ! lines — pasting them created stray files and ran npm install in the reader's own shell
• test-and-commit { was invalid bash; because it loads via BASH_ENV, it fired npm test on every shell command Copilot ran
• copilot --version exits before config init, so the ls $COPILOT_HOME step always failed
• --sandbox was silently ignored without --experimental
• MCP server name github → github-mcp-server

Validation

• Integration test: all 13 modules executed in the copilot-workshop container — 130 commands, 122 passed, 8 failed, 77 skipped (interactive-only; none auth-gated, nothing hung). All 8 failures are fixed in this PR.
• Spot-verified live: --share produced a valid transcript, --continue recovered a seeded codeword, --available-tools 'bash,view' genuinely restricted the tool list, GitHub MCP tool counts moved 5 → 0 → 46 as documented, and destructive rm/overwrite prompts were correctly blocked under default permissions.
• Static checks: cross-references, code fences, table columns, exercise numbering and Marp frontmatter all pass; workshop prose remains fully versionless.

Housekeeping

• Refreshed 11 redirecting docs.github.com URLs
• Synced all 13 slide decks; "Your Turn!" slides and Fluent styling intact
• Updated the validated CLI version in the instructions constant, README badge/text, and landing page