fix(ticket new): robust title parsing and concise ticket aliases

[heum-ilgugim]

Goal

Make gira ticket new reliable for natural positional-title command lines and provide concise aliases for the daily ticket-creation path.

Scope

• Fix positional-title parsing so every value-taking ticket new flag consumes its value before title detection, including --release-impact, --release-impact-reason, and --body-file -.
• Add concise, documented aliases for the daily ticket creation path without removing the canonical commands.
• Keep positional title and --title compatibility.
• Add table-driven CLI regressions for flag ordering, stdin body input, and aliases.

Non-goals

• Do not redesign all Gira command groups or remove canonical command names.
• Do not change ticket lifecycle policy, GitHub mutation behavior, or branch policy.

Acceptance Criteria

• gira ticket new "title" --release-impact internal --dry-run produces a ticket preview.
• gira ticket new --title "title" --release-impact internal --dry-run produces a ticket preview.
• --body-file - with a positional title and release-impact reads stdin and produces a preview.
• A concise alias can create the same dry-run ticket preview as gira ticket new, and help/guide output documents it.
• Existing canonical invocations remain compatible and go test ./... passes.

Doctor Impact

No doctor rule changes.

Expected Delivery

• One focused PR with CLI and documentation regression coverage.

Verification

• Focused CLI parser and alias tests.
• go test ./... and git diff --check.

Evidence

The v3.1.3 reproduction originally attributed the failure to --body-file -, but isolated verification shows stdin body input works. The standalone-space form --release-impact internal is parsed as an extra positional title; --release-impact=internal succeeds.

base_branch: main
base_source: branch_policy.repo_local_contract.default
branch_policy_mode: github-flow
target: default
work_branch: issue-942-fix-ticket-new-robust-title-parsing-and-concise-ticket-aliases
work_branch_source: current