Fix session-state table rendering on GitHub (#228)

* Trim redundant sections in README

Cut ~140 lines (1397 → 1254) by removing duplicated content while
keeping every feature reference and anchor intact:

- Linux install: drop per-distro install lists, keep headless example
- Command arguments: collapse Rules/shell-vars/pitfall (already
  covered by inline examples) into two prose lines
- Session lifecycle: drop bullet-list recap that duplicated the
  state table
- Authentication precedence: replace five "When X is specified"
  sub-blocks with a single flag table
- Scripting: dedupe the jq|xargs pipeline shown in both Code mode
  and Scripting
- MCP server config file: remove duplicated "Using servers" block

* Fix session-state table rendering on GitHub

The `**...**` bold markers were attached directly to the emoji with no
separating whitespace, so GitHub rendered the asterisks literally instead
of as bold. The backticked state names stand on their own; drop the bold.

Refs #227

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Co-authored-by: Claude <noreply@anthropic.com>