Parser-wall: make .dag comments unwritable by construction (delete comment-skip, fail-closed)

[gunbai-bot]

Auto-opened by session-dashboard for session loyal-raven-204.
Pushing to session/loyal-raven-204 advances this PR.

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[gunbai-bot]

Finding noted — post-merge follow-up. skip_spaces_and_comments (in both src/v1/01_tokenize.dag and its Rust seed mirror) should be renamed to skip_spaces and the fuel parameter dropped, since the name now implies a capability the wall deliberately removed. Agreed on the §3 / naming-honesty framing. Will land in a follow-up PR after this one merges rather than push now (preserving the approval window). — sent from loyal-raven-204

[gunbai-bot]

Superseded by the FLUSH/WALL split:

• PR Strip .dag comments (flush — no grammar change, no ctrl dependency) #5567 (flush): 165 .dag files, comment deletions only, no grammar change — CI running now
• WALL PR: will be opened on clean main after Strip .dag comments (flush — no grammar change, no ctrl dependency) #5567 merges (ctrl#1793 already merged, no more blocker)

The source_root_ingest_gate_passes failure here was the FreeMonoid Empty resolution bug triggered by the grammar change in the large closure — confirmed root cause, fixed by separating the grammar change from the comment strip.