feat(catalog): add red-team extension to community catalog (#2306)

* feat(catalog): add red-team extension

Adds the `red-team` community extension to the catalog:

- Adversarial review of functional specs before /speckit.plan locks in
  architecture.
- Complements /speckit.clarify (correctness) and /speckit.analyze
  (consistency) with parallel adversarial lens agents.
- One command: speckit.red-team.run
- MIT licensed; requires spec-kit >= 0.7.0.

Origin: this extension was originally proposed as a core command
(github/spec-kit#2303). Per maintainer guidance (mnriem's comment on
that PR), it's been restructured as a community extension hosted at
https://github.com/ashbrener/spec-kit-red-team.

Dogfood-validated on a 500-line functional spec: 5 lens agents
dispatched in parallel returned 25 findings in ~1.5 min wall-clock,
19 of which met the meaningful-finding bar (severity >= HIGH AND
novel adversarial angle that clarify/analyze structurally cannot
catch). Full detail in the extension's CHANGELOG.

* catalog: shorten red-team description to fit <200 char schema limit

Resolves Copilot review comment on #2306. Previous description (259
chars) exceeded the extensions/EXTENSION-PUBLISHING-GUIDE.md Appendix
schema ceiling. Shortened to 188 chars, keeping the distinctive
value proposition (adversarial, complements clarify/analyze) and
moving the per-phase mechanics to the extension's own README.

* catalog: bump red-team to v1.0.1 (lower required spec-kit version)

Follow-up to v1.0.0 catalog entry:
- version: 1.0.0 -> 1.0.1
- download_url: points at v1.0.1 release asset
- requires.speckit_version: >=0.7.0 -> >=0.1.0

The v1.0.0 requirement was too strict and blocked installation on
common 0.6.x field versions (confirmed via local install attempt).
The extension uses no 0.7.x-specific APIs; matches community norm
(reconcile, refine, others use >=0.1.0).

* catalog: bump red-team to v1.0.2 (adds mandatory before_plan gate)

v1.0.2 ships a /speckit.red-team.gate command wired as a mandatory
before_plan hook so /speckit.plan auto-invokes it on every run against
qualifying specs. Non-qualifying specs return PROCEED silently; qualifying
specs without findings on record return HALT with explicit remediation
(run /speckit.red-team.run, or opt out via --skip-red-team-gate: <reason>
which is recorded as an Accepted Risk [red-team-skipped] in the plan).

Catalog metadata delta:
- version: 1.0.1 -> 1.0.2
- download_url: v1.0.2/red-team-v1.0.2.zip
- provides.commands: 1 -> 2 (adds speckit.red-team.gate)
- provides.hooks: 0 -> 1 (adds before_plan hook)

No breaking changes. Projects that do not want the gate simply do not
install the extension.

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Co-authored-by: Ash Brener <ashley@midletearth.com>