docs: sync to Claude Code v2.1.206 (#151)

* docs: correct stale content for Claude Code v2.1.206

Fix content that no longer matches current Claude Code behavior:

- 04-subagents: remove the /agents creation-wizard instructions
  (wizard removed in v2.1.198); point users to ask Claude or edit
  .claude/agents/ files directly. Explore agent now inherits the
  session model (capped at Opus) instead of Haiku; subagents run in
  the background by default.
- Rename the default permission mode "default" -> "Manual" (v2.1.200)
  across README, CATALOG, INDEX, LEARNING-ROADMAP, resources,
  claude_concepts_guide, and 09-advanced-features, noting that
  "default" still works as an alias.
- README: update the stale "latest v2.1.160" currency claims to v2.1.206.
- Reconcile the contradictory /simplify vs /code-review history:
  they are distinct current skills (/simplify split back out in v2.1.154).

Refresh metadata footers to v2.1.206 / July 11, 2026 and add Claude
Sonnet 5 to Compatible Models on every edited file.

* docs: add Claude Code v2.1.206 feature coverage

Document new features and options that landed through v2.1.206:

- Skills: /dataviz bundled skill, skill stacking (loads all leading
  skills, up to 5), and the ${CLAUDE_PROJECT_DIR} substitution.
- Slash commands: /dataviz row and ${CLAUDE_PROJECT_DIR} mention.
- Subagents already covered in the correctness commit; CLI adds
  --append-subagent-system-prompt, CLAUDE_ENABLE_STREAM_WATCHDOG,
  a Claude Sonnet 5 model row (new default, 1M context), and the
  /model "Org default" note.
- MCP: roots/list working-directory discovery and the untrusted-
  workspace pending-approval behavior for self-approved .mcp.json.
- Hooks: agent_needs_input / agent_completed Notification values and
  the prompt_id input field.
- Plugins: marketplace renames / displayName / defaultEnabled fields.
- Checkpoints: "Summarize up to here" backward targeted compaction.

Refresh metadata footers to v2.1.206 / July 11, 2026 and add Claude
Sonnet 5 to Compatible Models on every edited file.

* docs: qualify Sonnet 5 default scope and reconcile bundled-skills list

- Sonnet 5 default is tier-dependent (Pro/Team seats); Opus 4.8 remains
  default on Max/Team Premium/Enterprise PAYG/API — was overstated as
  the flat default.
- Add missing /simplify row to the bundled-skills table (it was already
  referenced as a distinct skill in the /code-review row) and drop the
  hard skill count in favor of pointing at the commands reference.

CATALOG.md

@@ -127,7 +127,7 @@ Claude Code supports 6 permission modes that control how tool use is authorized.
 
 | Mode | Description | When to Use |
 |------|-------------|-------------|
-| `default` | Prompt for each tool call | Standard interactive use |
+| `manual` | Prompt for each tool call | Standard interactive use (renamed from `default` in v2.1.200; `default` still accepted) |
 | `acceptEdits` | Auto-accept file edits, prompt for others | Trusted editing workflows |
 | `plan` | Read-only tools only, no writes | Planning and exploration |
 | `auto` | Accept all tools without prompting | Fully autonomous operation (Research Preview) |
@@ -545,16 +545,17 @@ chmod +x ~/.claude/hooks/*.sh
 
 ---
 
-**Last Updated**: June 15, 2026
-**Claude Code Version**: 2.1.176
+**Last Updated**: July 11, 2026
+**Claude Code Version**: 2.1.206
 **Sources**:
 - https://code.claude.com/docs/en/overview
 - https://code.claude.com/docs/en/commands
 - https://code.claude.com/docs/en/hooks
+- https://code.claude.com/docs/en/permission-modes
 - https://code.claude.com/docs/en/changelog#2-1-172
 - https://code.claude.com/docs/en/changelog#2-1-174
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.145
 - https://github.com/anthropics/claude-code/releases/tag/v2.1.154
 - https://code.claude.com/docs/en/plugins
 - https://code.claude.com/docs/en/cli-reference
-**Compatible Models**: Claude Sonnet 4.6, Claude Opus 4.8, Claude Haiku 4.5
+**Compatible Models**: Claude Sonnet 5, Claude Sonnet 4.6, Claude Opus 4.8, Claude Haiku 4.5