fix(pull-sdlc): bootstrap on Windows emits ~60 LF->CRLF warnings (regression from #168 ahead of #161)

[MarkMichaelis]

Symptom

Running ./Pull-SDLC.ai.ps1 on a fresh Windows consumer (core.autocrlf=true)
emits ~60 warning: in the working copy of '...', LF will be replaced by CRLF the next time Git touches it
warnings during the bootstrap commit, and the consumer is left with no line-ending normalization.

Sample (truncated) from a real run on commit f7d1f13:

Files to update: 87 (syncing (empty tree) -> f7d1f13)
  A: 87
...
Applied 87 ops.
Merged upstream entries into .gitignore
warning: in the working copy of '.github/agents/plan.agent.md', LF will be replaced by CRLF the next time Git touches it
warning: in the working copy of '.github/instructions/copilot-coding-agent.instructions.md', LF will be replaced by CRLF the next time Git touches it
...
warning: in the working copy of '.sdlc-ai-sync.json', LF will be replaced by CRLF the next time Git touches it
Created sync commit: d1dc143

Root cause

PR #168 (refactor(Pull-SDLC): remove .gitattributes scaffolding, merged
2026-05-30) removed the .gitattributes.template -> .gitattributes
scaffold from Pull-SDLC.ai.ps1 on the premise that the replacement,
Initialize-GitDefaults.ps1 (PR #161), would own that file going forward.

But PR #161 is still open and unmerged. Net effect on main today:

• .gitattributes.template is gone (PR refactor(Pull-SDLC): remove .gitattributes scaffolding #168 deleted it)
• Initialize-GitDefaults.ps1 does not exist on main (PR feat: Initialize-GitDefaults.ps1 -- compose .gitattributes/.gitignore from upstream templates #161 not merged)
• Write-NextStepsBanner has no Write-GitDefaultsHint call (would
  have been added by PR feat: Initialize-GitDefaults.ps1 -- compose .gitattributes/.gitignore from upstream templates #161)

So a fresh consumer bootstraps with zero normalization tooling and is
greeted by a wall of LF/CRLF warnings the first time the sync commit lands.

Impact

• Every from-zero Windows bootstrap since PR refactor(Pull-SDLC): remove .gitattributes scaffolding #168 merged (2026-05-30).
• Consumer repo silently inherits whatever core.autocrlf the local
  machine has set, with no project-level override. Cross-platform contributors
  on the same consumer repo will diverge.
• Undermines the "just works" onboarding goal (issue fix(pull-sdlc): scratch-state auto-recovery (force-with-lease + autocrlf hash + no silent downgrade) #133).

Fix options

1. Land PR feat: Initialize-GitDefaults.ps1 -- compose .gitattributes/.gitignore from upstream templates #161 (preferred) -- that PR is the intended owner of
   .gitattributes and adds the Write-GitDefaultsHint next-steps line
   that closes the gap.
2. Temporary scaffold restore -- if feat: Initialize-GitDefaults.ps1 -- compose .gitattributes/.gitignore from upstream templates #161 needs more review time, restore
   a minimal .gitattributes.template (just * text=auto eol=lf and a
   *.ps1 text eol=lf line) and put it back in \ /
   \. Revert when feat: Initialize-GitDefaults.ps1 -- compose .gitattributes/.gitignore from upstream templates #161 lands.

Related improvements spotted during triage

These are smaller polish items observed while investigating; happy to split
into separate issues if preferred.

• Next-steps banner is missing the pre-commit hook activation step.
  CLAUDE.md mandates git config core.hooksPath .githooks "Before ANY
  commit", but Write-NextStepsBanner never mentions it. New consumers
  trip the very rule the hook is meant to enforce.
• Suggested bootstrap commit message has no Conventional-Commits scope.
  Current text is chore: scaffold IntelliSDLC.ai consumer files;
  project convention is type(scope): description. Suggest
  chore(sdlc-ai): bootstrap consumer files.
• "Existing upstream-managed files were detected" wording is misleading
  when the op list is 100% A: (adds). Showing which file(s) triggered
  the detection (typically a stray Pull-SDLC.ai.ps1 from a manual
  download) would let the user confirm nothing valuable will be clobbered.
• Yellow bootstrap-prompt banner reads like an error. "No
  .sdlc-ai-sync.json and no prior sync commit found." has caused at
  least one reader to ask "wasn't this file removed?". Recommend rephrasing
  to [Bootstrap] No prior sync anchor found.

Repro

1. On Windows with git config --global core.autocrlf true (default),
   create an empty directory and git init it.
2. Drop Pull-SDLC.ai.ps1 from upstream main and run it.
3. Observe the LF->CRLF warning wall during git commit.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com