feat: MCP server, README overhaul, CHANGELOG v4.1.0, stashed rule updates

[gauravs19]

Summary

MCP Server (mcp_server.py) — new

• Exposes all 37 rules, 17 templates, and 5 personas as MCP resources over stdio transport
• Resources: archpilot://rules/index, archpilot://rules/{name}, archpilot://templates/{name}, archpilot://personas/{name}, archpilot://diagrams/{name}
• Tools: list_rules(), get_rule(name), list_templates(), list_personas(), run_lint(dir, tier) → JSON, calculate_nfrs(tps, ...) → physics output
• Fuzzy rule lookup: accepts bare name, numeric prefix ("03"), or full filename ("03-hld-standards.md")
• One-line Claude Code setup: add archpilot to ~/.claude/settings.json mcpServers
• requirements.txt + pyproject.toml: added mcp>=1.0.0

README — overhauled

• Install section: pip install -e . as primary path; archpilot CLI shown throughout
• Quick Start: all new flags documented (--from-phase, --max-tokens, --format json, --model)
• What is Archpilot table: added MCP Server as third mode
• Standards Library: complete options list — A=Claude, B=Copilot, C=Cursor, D=Kiro, E=ChatGPT, F=Gemini, G=Windsurf, H=Aider, I=MCP Server
• New Personas section: table of all 5 personas with clear descriptions — previously buried and undiscoverable
• File tree: updated with mcp_server.py, pyproject.toml, 3 new LLM configs, expanded persona descriptions
• Total count: corrected to 37 rules | 17 templates | 8 LLM configs | 5 personas | MCP server

CHANGELOG — v4.1.0 entry added

Documents all changes from PRs #5, #6, and this PR.
MCP Server removed from Unreleased Planned (now shipped).

Stashed local improvements committed

• rules/00-architecture-principles.md: 7 additions
• rules/27-spec-driven-development.md: 29 additions
• tools/nfr_calculator.py: refactor
• docs/index.html: footer tweak

Test plan

• python mcp_server.py starts without errors (requires pip install mcp)
• Add to Claude Code settings and verify list_rules() tool appears in /tools
• get_rule("03") returns content of 03-hld-standards.md (numeric prefix lookup)
• run_lint(".", 2) returns valid JSON with passed, errors, warnings keys
• README renders correctly on GitHub — no broken links in new Personas section
• archpilot --version prints archpilot 4.1.0