docs: phase 6 — mkdocstrings API reference (#10)

docs/reference/api.md, with mkdocstrings directives covering every
public name re-exported from yarlpattern/__init__.py — tiered by
audience:

* Primary API — URLPattern, URLPatternResult, COMPONENTS
* Escape helpers — escape_pattern_string, escape_regexp_string
* Low-level building blocks (tokenizer / parts / regex generation) —
  for tools that compose URLPatterns programmatically

Auto-extracted from the existing Google-style docstrings. Future API
changes to docstrings ship to the site on the next push to main with
zero hand-maintained reference content to drift.

properdocs nav gains a Reference > API entry between WPT Conformance
and Comparisons. Phase 6 task #48 closed.

With Phase 6 merged the documentation arc is complete:

  Overview (URLPattern-101 + ecosystem)
  Examples (11 verified worked examples)
  Reference (auto-extracted API)
  Comparisons (vs aiohttp UrlDispatcher, vs yarl)
  Explanation (architecture)
  WPT Conformance (auto-generated)

Co-authored-by: chad-loder <26261238+chad-loder@users.noreply.github.com>

Author: chad-loder

docs/reference/api.md

@@ -0,0 +1,133 @@
+# API reference
+
+Auto-extracted from yarlpattern's docstrings by
+[mkdocstrings](https://mkdocstrings.github.io). Items are grouped by
+audience: the primary public API, the escape helpers most callers
+eventually need, and the lower-level building blocks reserved for
+advanced use.
+
+## Primary API
+
+The 95% surface: one class, one result type, one tuple of component
+names.
+
+::: yarlpattern.URLPattern
+    options:
+      show_source: false
+      show_root_heading: true
+      members_order: source
+
+::: yarlpattern.URLPatternResult
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.COMPONENTS
+    options:
+      show_source: false
+      show_root_heading: true
+
+## Escape helpers
+
+When you're building a pattern from a string whose contents might
+contain pattern metacharacters (`:`, `*`, `(`, `)`, `{`, `}`), escape
+it first.
+
+::: yarlpattern.escape_pattern_string
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.escape_regexp_string
+    options:
+      show_source: false
+      show_root_heading: true
+
+## Low-level building blocks
+
+The spec-aligned tokenizer, parser, and regex generator are public
+because they're useful for tools that compose URLPatterns
+programmatically — a route-table linter, a static analyzer for
+overlapping patterns, a code generator emitting JavaScript URLPattern
+strings from a Python source of truth.
+
+Most users never need these.
+
+### Tokenizer
+
+::: yarlpattern.tokenize
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.Token
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.TokenType
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.TokenizePolicy
+    options:
+      show_source: false
+      show_root_heading: true
+
+### Parts
+
+A *part* is one syntactic element of a pattern: a literal text run,
+a named segment-wildcard, a regex group, or a full wildcard.
+
+::: yarlpattern.parse_pattern_string
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.parts_to_pattern_string
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.Part
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.PartType
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.PartModifier
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.Options
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.EncodingCallback
+    options:
+      show_source: false
+      show_root_heading: true
+
+### Regex generation
+
+::: yarlpattern.parts_to_regex
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.generate_segment_wildcard_regexp
+    options:
+      show_source: false
+      show_root_heading: true
+
+::: yarlpattern.FULL_WILDCARD_REGEXP_VALUE
+    options:
+      show_source: false
+      show_root_heading: true

properdocs.yml

@@ -89,6 +89,8 @@ nav:
       - Extract YouTube video IDs from any URL form: examples/extract-youtube-video-ids-from-any-url-form.md
       - Match Slack callback IDs with structured data: examples/match-slack-callback-ids-with-structured-data.md
   - WPT Conformance: wpt-compliance.md
+  - Reference:
+      - API: reference/api.md
   - Comparisons:
       - vs. aiohttp.web.UrlDispatcher: comparisons/aiohttp.md
       - vs. yarl: comparisons/yarl.md