docs: clarify that standard-library modules lead the use case outright

Maintainer correction to the previous amendment: stdlib sorts at the
top of the whole use case, not merely first within its tier. No README
movement results — the stdlib admission rule (a standard-library
module is listed only where it is itself the obvious choice) means
every stdlib entry already sits in the first tier, so tier-top and
use-case-top coincide; the rule text now states the intent directly.

Co-Authored-By: Claude <noreply@anthropic.com>

CONTEXT.md

@@ -44,7 +44,7 @@ The only admission path into a full Use Case: the PR names the entry it replaces
 _Avoid_: One-in-one-out (informal alias)
 
 **Challenger**:
-An entry (at most two per Use Case) that is not yet the Obvious Choice but is a credible successor to one. Marked by ordering, not description: within a Use Case, Obvious Choices are listed first, then Challengers, each tier by PyPI downloads/month descending (standard-library modules first in tier, other no-signal entries last in tier, alphabetically). Admission requires adoption-trajectory evidence, not popularity alone.
+An entry (at most two per Use Case) that is not yet the Obvious Choice but is a credible successor to one. Marked by ordering, not description: within a Use Case, Obvious Choices are listed first, then Challengers, each tier by PyPI downloads/month descending (standard-library modules first in the Use Case outright — always Obvious Choices by the stdlib rule — other no-signal entries last in tier, alphabetically). Admission requires adoption-trajectory evidence, not popularity alone.
 _Avoid_: Rising Star (old lane name), Hidden Gem (old lane name — concept removed entirely)
 
 **Second Tier**:

CONTRIBUTING.md

@@ -29,7 +29,7 @@ Hard maximum: 5 entries per use case. This is a qualitative bar first and a nume
 
 **Evidence**: admission is decided by maintainer editorial judgment, informed primarily by PyPI download counts rather than GitHub stars. Judgment overrides the signal's known failure modes (CI-inflated counts, model releases consumed as weights rather than pip installs, large-but-specific audiences misread as "niche"). The maintainer's decision is final.
 
-Looking for an exhaustive catalog instead? Follow the awesome-* lists linked under individual entries (for example awesome-python-testing) — they exist precisely so this list doesn't have to be one.
+Looking for an exhaustive catalog instead? Follow the awesome-\* lists linked under individual entries (for example awesome-python-testing) — they exist precisely so this list doesn't have to be one.
 
 ## Entry Format Reference
 
@@ -73,7 +73,7 @@ Use the **PyPI package name** as the display name so developers can copy it dire
 
 ### Entry Ordering
 
-Within a use case, the obvious choices are listed first, ordered by PyPI downloads per month from high to low; challengers follow, in the same order. Standard-library modules sort first within their tier — built-ins lead — alphabetically when there are several. Other entries without a download signal (agent skill packs, projects distributed outside PyPI) sort last within their tier, alphabetically. There is no marker in the entry text — position is the marker, so the last entries of a use case may be its challengers.
+Within a use case, the obvious choices are listed first, ordered by PyPI downloads per month from high to low; challengers follow, in the same order. Standard-library modules sort first in the use case — built-ins lead, before everything else — alphabetically when there are several. (This never conflicts with tier order: a standard-library module is only listed where it is itself the obvious choice, so it always belongs to the first tier.) Other entries without a download signal (agent skill packs, projects distributed outside PyPI) sort last within their tier, alphabetically. There is no marker in the entry text — position is the marker, so the last entries of a use case may be its challengers.
 
 ## Changing the Structure