Fix wrapped publisher content decoding

[yihanzhu]

Closes #196

Follow-up to #192.

GitHub Contents API returns Base64 content with line breaks. This change removes permitted ASCII Base64 whitespace before decoding while preserving response validation and fail-closed invalid-data behavior.

Scope:

• fix the publisher content decoder
• cover line-wrapped and invalid Base64 responses

Targeted proof on the candidate:

• publisher gate tests: 134 passed, 0 failed
• ShellCheck 0.11.0: clean
• diff and two-file scope checks: clean

[yihanzhu]

Codex reviewer (cross-vendor, read-only)

Reviewed-head: 30ed5c8
Reviewed-base: 3dbd969
reviewer: operator-default @ high

Posted verbatim by codex-review.sh (codex exec review --json --base refs/codex-review/197-96059/base in an isolated temp worktree, sandbox forced read-only). Comments only — Codex never pushes, approves, or merges.

The change correctly normalizes whitespace in GitHub's line-wrapped Base64 content before decoding. The added tests cover wrapped content and invalid Base64 without introducing observable regressions.

[yihanzhu]

One-time publisher recovery merge required

PR #197 is ready for squash merge.

• exact head: 30ed5c8
• exact base: 3dbd969
• scope: two publisher files only
• required ci: SUCCESS, run 33314034985, app 15368
• final review: clean, comment 5468963455

The installed #192 gate fails before it can emit a connector request because its own GitHub-content decoder is the bug fixed here. Using another write path would violate the gate contract, so the construction publisher fails closed. Please squash-merge this exact unchanged repair once. After receipt verification, #195 will refresh onto the repaired main and normal automatic publishing will resume.

[yihanzhu]

Recovery merge receipt: reviewed head 30ed5c8 on base 3dbd969 squash-merged as d705741. Merge parent equals reviewed base; merge tree 66370a04fa19977ff9d4fb6c656eadd4d11dabd4 equals reviewed head tree; fetched main equals the merge commit. Installed gate blob is now 57de15b3dfe1993efb46bed671608389de66f278.