chore: track GSD planning docs (un-ignore .planning + docs/superpowers)

[HanSur94]

What & why

.gitignore has been silently swallowing GSD planning docs since #61, which added .planning/, .superpowers/, and docs/superpowers/ as "local workflow artifacts."

The catch: git only ignores untracked files. When that rule landed, 75 .planning files were already tracked, so they kept getting committed — while every planning doc created afterward was hidden. The result in the main checkout:

dir	on disk	tracked	hidden
.planning/	483	75	408
docs/superpowers/	1	0	1
.superpowers/	0	0	0 (empty)

That's ~6.8 MB of planning history (PROJECT.md, MILESTONES.md, config.json, REQUIREMENTS/ROADMAP/STATE, codebase/, debug/, milestones/, research/, and the phases/ + quick/ dirs) that never made it into the repo.

Change

• Remove the .planning/ and docs/superpowers/ ignore rules.
• Commit the 409 previously-hidden planning docs (all Markdown/JSON, no binaries, largest file 84 KB).
• Leave .superpowers/ ignored — it's empty, and is brainstorm scratch rather than durable planning output.

Notes

• Scanned the added content for secrets (token prefixes, private-key blocks, ANTHROPIC_API_KEY=) — none found.
• Big diff by file count (410 files) but it's all docs; no source/code touched besides the two .gitignore lines.
• Going forward, GSD-generated planning docs will show up in git status instead of being silently ignored.

🤖 Generated with Claude Code

[HanSur94]

ℹ️ Heads-up: the failing "Example Smoke Tests" check is pre-existing on main, not introduced by this PR.

This change is docs-only (un-ignores .planning/ + docs/superpowers/ and commits the previously-hidden GSD planning docs — no source touched besides two .gitignore lines).

The same workflow is already red on main — including 99d138fa, the exact commit this branch was cut from, plus the two commits before it. The failure is:

example_dock → Tab 2 "Power Systems", tile 1 → Vectors must be the same length.
(examples/01-basics/example_dock.m)

That's an unrelated example/engine bug and is best fixed in its own PR rather than bundled here.