Auto-parity was trunk-scoped (mi350 only). mi300/mi200/navi31 run in their
own scheduled upstream workflows on their own SHAs at a different cadence,
so the trunk-push scan never reached them.

- Discover candidate SHAs from both trunk.yml pushes and the scheduled
  per-arch workflows (fetch_scheduled_commits / fetch_candidate_commits),
  deduped newest-first; a 40-hex guard drops stray non-row output.
- Hold back SHAs newer than the newest scheduled run so a lagging
  mi300/mi200/navi batch can still join that SHA's report, yielding ONE
  combined parity report per SHA (parity.yml's matrix already emits a
  per-arch artifact plus a merged summary) once every arch that ran has
  finished. When no scheduled runs exist, nothing is held (mi350/trunk
  behaves exactly as before).
- Expand ARCHS_IN to mi350 mi300 mi200 navi31.
- Per-config CUDA-baseline gating: a SHA whose CUDA jobs for a test config
  did not run (e.g. a failed trunk run that never launched CUDA default)
  has no baseline for that config, so exclude just that config from the
  dispatch (via parity.yml's exclude_* inputs) instead of emitting a bogus
  all-MISSED column, and drop its ROCm shards from the completion gate.

No parity_job_config.json change: mi300 has no fallback; its default/
distributed/inductor come from rocm-mi300 / periodic-rocm-mi300 /
inductor-rocm-mi300, which run together on one scheduled SHA.

Shard counts were hardcoded (config value or literals), so when an arch
falls back to a different workflow whose sharding differs, the constructed
"(config, i, N)" job/artifact keys miss the real jobs. Concretely mi200's
default/inductor workflows are dormant upstream and fall back to
trunk-rocm-sandbox, which shards default into 10 (config says 6) and
inductor into 4 (config says 2) - so every key "DOES NOT EXIST IN JOBS"
and the mi200 shard of a combined auto report fails.

Add derive_shard_count(), which reads the actual shard total from the
resolved run's job names, and use it for ROCm default/distributed/inductor
(falling back to the config value only when no matching jobs are found).
This unblocks mi200 in the multi-arch auto-trigger.

The DISAGREE/AGREE metric counted a ROCm SKIPPED or MISSED test as a
disagreement whenever CUDA merely did not SKIP it - which includes the
large set of attention-backend parametrization variants CUDA never even
enumerates (CUDA MISSED). Those are not real ROCm-vs-CUDA coverage gaps and
inflated DISAGREE to ~3% (AGREE ~97%).

Count a disagreement only when CUDA actually PASSED the test (s2 == PASSED)
in both compute_test_config_stats and compute_overall_stats, and relabel the
two line items accordingly ('PASSED on <set2>'). This matches the triage
spreadsheet's adjusted definition; AGREE% becomes ~99%.

The HUD link added in pytorch#3258 was lost when parity.yml was rewritten. Re-add it in generate_summary.py (next to the Commit SHA header) so it lives in the report itself (step summary + CSV artifact) and survives workflow rewrites. The link targets the upstream HUD page for the resolved commit, regex-filtered to the trunk CUDA/inductor/rocm test jobs the report is built from. Parens/pipes are percent-encoded to keep the markdown link valid; normal runs already pass set1_name=rocm/set2_name=cuda. Verified end-to-end against a real mi350 status CSV.

Consumer-side support for commit-vs-commit parity (baseline_sha mode):

- detect_log_failures.py: preserve the short commit-SHA prefix on log
  filenames (e.g. 09e0c59b_rocm3.txt) as the platform label, matching the
  SHA-prefixed filenames download_testlogs produces in baseline mode.
- summarize_xml_testreports.py: name the per-test-file running-time CSV
  columns from the resolved set names (set1/set2) instead of hardcoded
  rocm_/cuda_, and add per-config test-shard counts.

The download_testlogs run-selection side of this work already landed in
develop via pytorch#3278, so this PR carries only the remaining consumer-side
parsing changes.

The running-time CSV columns use set1_name/set2_name (rocm/cuda by default, commit SHAs in commit-vs-commit mode), but the printed summary still hardcoded ROCM/CUDA. Drive the user-facing summary headers from the same set names so both stay consistent; normal-mode output is unchanged (rocm/cuda).

Adds a "preview" ROCm arch so parity can be run against the upstream
rocm-preview lane (linux-noble-rocm-preview-py3.12-gfx942, gfx942), which
runs the TheRock preview wheel (e.g. ROCm 7.14) via the ciflow/rocm-preview
label. default/distributed/inductor all come from the single rocm-preview
workflow (6/3/2 shards).

- parity_job_config.json: new rocm.preview entry.
- download_testlogs: allow --arch preview.
- parity.yml: list preview as an arch option.

Because rocm-preview is ciflow-triggered (not scheduled on main), this arch
is for manual/on-demand parity runs against a rocm-preview commit; it is
intentionally not added to the auto-trigger scope.

test_conv2d_backward_parametrized is skipped on ROCm via skipIfRocmArch
(upstream pytorch#188671, CI timeout). It was falling into the generic Misc
bucket; add a Tier-1 rule so conv2d_backward gfx-arch skips are categorized
as 'PT2.0 - Convolution' instead. Non-conv2d gfx skips stay Misc.

Flip the parity.yml auto_classify input default false->true so skip-reason
classification runs on every dispatch, including autoparity commits (which
don't pass the input and so inherit the default). Previously auto runs left
skip_reason blank; now the disagreement subset (SKIPPED/MISSED on ROCm +
PASSED on CUDA) is categorized automatically.

…istributed config

pytorch#189232 hived single-GPU distributed tests out of the 'distributed'
config onto CUDA's 1-GPU 'default' runner, while ROCm still runs the whole
distributed suite under 'distributed'. Our (test, config) keying then can't
match a CUDA-'default' result with the ROCm-'distributed' result, so the same
passing test double-counts as MISSED on both sides (~1700 spurious mi350
disagreements starting 07/11).

Canonicalize default -> distributed for distributed.* test files so the two
stacks line up again. Scoped to distributed.* files only, leaving genuine
default/inductor results untouched.