Add repo-standardizer skill: polish any GitHub repo surface (#2715)

* Add repo-standardizer skill: polish any GitHub repo surface

* fix(skill): remove non-string metadata and fix template README refs for vally lint

* docs(skill): drop markdown relative links from README language-switcher example

Vally valid-refs flagged ./README.md and ./README.zh.md as missing file
references; they are generated artifacts, not skill files. Keep the
example as plain text to satisfy the linter.

* fix(template): add missing language switcher to English README template

Align with README.zh.md template and SKILL.md switcher convention:
current language as plain text, other languages as relative links.

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Co-authored-by: programmingWTF <programmingWTF@users.noreply.github.com>

skills/repo-standardizer/templates/LABELS.md

@@ -0,0 +1,47 @@
+# Label Guide
+
+Every label in this repository, what it means, and how it ranks. Rating
+tiers always carry emoji prefixes with a low→high gradient; other
+labels may or may not — per dimension, either all labels carry an emoji or
+none do, never mixed. Write labels in the repo's primary language.
+
+## Priority (P0 → P3)
+
+| Label | Meaning |
+|---|---|
+| `P0` | Emergency: data loss, security bypass, crash loop, unusable core |
+| `P1` | High: blocks planned work, needs attention soon |
+| `P2` | Medium: normal priority |
+| `P3` | Low: nice to have |
+
+## Impact (severity)
+
+| Label | Meaning |
+|---|---|
+| `impact: security` | Security boundary, credentials, authz, sandbox, sensitive data |
+| `impact: data-loss` | Loses, corrupts, or drops user/session/config data |
+| `impact: availability` | Crash, hang, restart loop, or process outage |
+
+## Rating labels (low → high)
+
+| Rank | Label | Meaning |
+|---|---|---|
+| 1 | `rating: <emoji> <name>` | lowest tier — describe what it means |
+| 2 | `rating: <emoji> <name>` | ... |
+| 3 | `rating: <emoji> <name>` | ... |
+| ... | ... | highest tier — describe what it means |
+
+> Rating tiers are the only labels that MUST carry an emoji — the low→high
+> gradient makes the ranking unambiguous.
+
+## Other labels
+
+| Label | Meaning |
+|---|---|
+| `bug` | Something isn't working as expected |
+| `enhancement` | New feature or request |
+| `documentation` | Improvements or additions to documentation |
+| `status: ready to merge` | Approved and ready to merge |
+| ... | ... |
+
+> Maintained by repo-standardizer — keep in sync whenever labels change.