refactor(cli): split the run() god-function into a dispatch table (H3)

[CodeWithJuber]

What & why

Fixes H3 from the deep review — the 2,420-line run() god-function in src/cli.js
(97% of the file; a flat 44-branch if (cmd === …) chain the review flagged as
"unreviewable, a merge-conflict magnet, boilerplate per new command").

run() is now a ~44-line dispatcher: it looks the command up in a HANDLERS map and
delegates. Each command is a module-scope async (argv, cmd) handler — independently
navigable (jump to HANDLERS.verify) and independently mergeable, which ends the
merge-conflict-magnet problem.

Behavior is byte-identical. Same argv in → same stdout/stderr/exit-code out. The
contract the whole test estate relies on (35+ files spawn node src/cli.js <args> and
assert output/exit codes) is unchanged and green. Preserved exactly:

• pre-dispatch middleware (--help/-h interception, first-run hint, the cortex-mcp
  server exemption) runs before the table lookup;
• the unknown-command suggestion + the "not wired yet" non-zero-exit fallback;
• the process.exitCode (never process.exit()) error model;
• the symlink-resolving main-module import guard (importing the package root still does
  not execute the CLI).

Handler signatures are trimmed to the params each body actually uses, so the refactor
introduces no unused-parameter warnings (biome stays at its baseline 10 warnings, 0
errors).

Checklist

• npm test passes (1069 pass / 0 fail / 2 gated skips)
• npm run check passes (Biome — 0 errors)
• Conventional commit message
• CHANGELOG.md updated under ## [Unreleased]
• No new runtime dependency
• Substrate/docs updated if affected (n/a — pure internal restructure)

Risk & rollback

• Risk level: low — pure mechanical restructure, no behavior change, full suite green.
• Rollback plan: revert the single commit; no data/schema changes.

Extra checks

• npm run typecheck passes
• node src/cli.js docs check green
• Importing the package root does not execute the CLI (M1 guard intact)
• Verified dispatch smokes: --help, brand, catalog, verify --json, unknown-command → exit 1

🤖 Generated with Claude Code

https://claude.ai/code/session_01C7htTiesXKLvAUtv6ET2jz

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Generated by Claude Code