tutorials: stale-comment + panic-model fixes (audit followup)

[borisbat]

Tier-C quick-win followup to the tutorial gap audit (#3125): four small, low-risk fixes that the audit flagged but were out of scope for the main PR (source-file comments and one doc note). Each claim was verified against source before editing.

Changes

File	Fix	Verified against
tutorials/language/30_json.das	Variant output comment was missing the $variant discriminator — actual output is {"$variant":0,"circle":5}	ran the tutorial
tutorials/dasStbImage/03_transforms.das	Default resize filter is Catmull-Rom only when upscaling, Mitchell when downscaling (the tutorial's resize(16,16) downsamples a 64×64, so it actually uses Mitchell)	stb_image_resize2.h 846-852 + filter resolution at 6578
tutorials/integration/c/03_binding_types.c	das_enumeration_make's third arg is the boolean ext (non-zero = int64 storage), not a 0=int8/1=int32/2=int16 selector	include/daScript/daScriptC.h:382
doc/source/reference/tutorials/21_error_handling.rst	Added a note: try/recover resumes mechanically, but a panic means a broken program — recover is for diagnostics-before-exit, not soft-error recovery; soft errors → Option/Result	CLAUDE.md panic model; probe-confirmed control flow

Not changed (audit over-flag)

The audit also flagged 09_aot.c's daslang.exe -aot script.das script.das.cpp line as wrong. It isn't — that direct form is valid (utils/daScript/main.cpp:510-515 routes argv[1] == "-aot" to das_aot_main). The RST shows the alternate utils/aot/main.das -- -aot ... form; both work. Left as-is.

Verification

preflight --only format,lint,docs — 8 passed, 0 failed (both sphinx-html and sphinx-latex with -W; only pdflatex skipped — no local TeX). The two .das edits are comment-only; the .c edit is comment-only.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Follow-up tutorial/documentation correctness fixes from the tutorial gap audit, focusing on aligning tutorial comments/notes with actual runtime/library behavior.

Changes:

• Update 30_json.das variant JSON output comment to include the $variant discriminator.
• Clarify dasStbImage resize default filter behavior (upsample vs downsample).
• Correct the das_enumeration_make “ext” argument description in the C integration tutorial.
• Add a note to the error handling RST about panic semantics and appropriate use of recover.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
tutorials/language/30_json.das	Fixes the documented JSON output for variants to match the serializer’s $variant encoding.
tutorials/integration/c/03_binding_types.c	Corrects the explanation of das_enumeration_make(..., ext) to match the C API contract.
tutorials/dasStbImage/03_transforms.das	Clarifies the default resize filter selection depending on scaling direction.
doc/source/reference/tutorials/21_error_handling.rst	Adds a panic-model note about try/recover usage; suggests a small wording clarification.

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