docs(standard): screenshot-free UI documentation standard + UI-label gate

The planned Playwright screenshot docs (SCREENSHOT_AUTOMATION.md) are
replaced by a text standard: screenshots rot silently and cannot be
gate-checked, while this UI's labels are server-rendered templ literals
that can. Layers: pattern-first prose (concepts survive redesigns) >
capability inventory > label->outcome flows > quoted labels > generated
references where a registry exists (filters/fields.md precedent). The
filter docs stay hands-off exemplars; user-doc tone is plain language by
contract, dev/admin tone explicitly deferred.

writing-ui-docs.md is the standard (page template, findability notes,
tone-by-audience, process rule: a UI change is not done until the docs
audit runs). ui-controls.md is the canonical control-label glossary the
docs quote from; TestUIControlLabels greps every entry against
templates/*.templ (source: ts override; also:-fragments for
Alpine-composed labels like the Match/Group header) so renames fail
make test in the same commit as the rename. Gate proven both ways: a
planted bogus label failed; restored set passes.

docs/developer/ui-controls.md

@@ -0,0 +1,166 @@
+<!-- Gate-checked by TestUIControlLabels (internal/docs/ui_labels_test.go):
+     every `controls` entry must exist as a literal in templates/*.templ
+     (or web/src for source: ts). Renames fail make test. Entry text is the
+     canonical spelling cited across the docs. -->
+
+# UI controls glossary
+
+The canonical spellings for controls cited across the UI documentation. Docs
+quote the label exactly as this page lists it — one entry per control; two
+spellings of one control is a defect. The `controls` block is machine-read:
+when a doc first names a control, add its entry in the same commit; when a
+rename lands, update the entry in the same commit and the gate goes green
+again.
+
+Entry fields:
+
+- `label` — the exact rendered text users see
+- `where` — semantic path (page → section/card), never spatial; see the
+  [writing standard](writing-ui-docs.md)
+- `does` — what interacting with it produces (the outcome)
+- `source` — optional; default `templ` (`templates/*.templ`); `ts` searches `web/src`
+- `also` — optional, pipe-separated extra literal fragments to search when
+  the visible label is Alpine-composed rather than static (OR-checked with `label`)
+- `note` — optional clarifier
+
+Form-field labels inside a single modal (Name, Description…) are cited
+inline in docs and not tracked here; this list carries the controls people
+navigate by.
+
+## Collections
+
+```controls
+label: New Collection
+where: Collections page
+does: Opens the create-collection modal.
+note: the empty page offers the same action as "Create Your First Collection"
+
+label: Create Your First Collection
+where: Collections page, when no collections exist
+does: Opens the create-collection modal.
+
+label: Create Collection
+where: create-collection modal → submit
+does: Saves the new collection and returns to the Collections page.
+
+label: Update Collection
+where: edit-collection modal → submit
+does: Saves your changes to the collection.
+
+label: Static
+where: create-collection modal → Type
+does: Chooses a hand-picked collection — you add and remove items yourself.
+
+label: ⚡ Smart
+where: create-collection modal → Type; also shown as a badge on smart collections page and detail
+does: Chooses a rules-matched collection — its membership stays current by itself.
+
+label: Rules scope
+where: create-collection modal, when Smart is chosen
+does: Asks what the rules ask about — the two buttons below it.
+also: 📚 Books|🎧 Podcast episodes
+note: "Books" and "Podcast episodes" as the two scope buttons
+
+label: Restore System
+where: Collections page
+does: Opens a pick-a-shelf modal to bring back a system collection you deleted.
+
+label: Restore
+where: Restore System Collection modal → submit
+does: Brings the selected system collection back.
+
+label: Edit Rules
+where: collection detail page
+does: Opens the smart-collection rules editor for this collection.
+
+label: Filter tree
+where: smart-collection rules editor
+does: The area where the group and rules are built.
+note: read/write rules — the how is the filter guide
+
+label: Apply to Collection
+where: smart-collection rules editor → save
+does: Saves the filter tree and makes the collection match those rules from now on.
+
+label: Add Items
+where: collection detail page
+does: Opens the item picker window.
+
+label: Add Selected
+where: item picker → footer
+does: Adds everything checked in the picker to the collection.
+
+label: Remove Selected
+where: collection detail page
+does: Opens a confirm dialog to remove the checked items from the collection.
+
+label: Search within collection...
+where: collection detail page → search box
+does: Filters the displayed items — nothing is removed.
+
+label: Play as Sequence
+where: collection detail page (when it has a downloaded episode)
+does: Plays the collection's episodes one after another in the listening order you pick.
+
+label: Hide finished books (reading-queue mode)
+where: edit-collection modal
+does: Finished books disappear from the collection's shelf.
+
+label: Show Up Next strip
+where: edit-collection modal
+does: Adds this collection's Up Next strip to the podcast page.
+```
+
+## Everywhere else
+
+```controls
+label: Filters
+where: All Books / Podcasts page → toolbar
+does: Opens the filter drawer for building and applying rules.
+
+label: Register Device
+where: Devices page
+does: Submits a device registration request for the pending-approval flow.
+
+label: Download All
+where: Podcast page → episodes area
+does: Queues every episode of the feed for download.
+
+label: Download order
+where: Podcast page → feed settings
+does: Sets the ordering used when feed episodes are downloaded.
+
+label: Match ALL / Group ANY header
+where: filter drawer → group header (also smart collections → Rules and dashboard sections)
+does: Sets how the group combines its rules; clicking the header flips ALL/ANY.
+also: ? 'Match' : 'Group'|? 'ANY' : 'ALL'
+note: label is Alpine-composed — 'Match' for the whole builder, 'Group' for nested; docs write it as MATCH ALL / MATCH ANY
+
+label: Reset to Scanned
+where: book detail → edit modal → scan information area
+does: Restores scanner-extracted metadata over manual edits.
+
+label: Auto-Scan
+where: Settings page → Scanning section
+does: Enables automatic periodic library scanning on the interval below it.
+
+label: Scan Interval (seconds)
+where: Settings page → Scanning section
+does: Sets the seconds between automatic scans.
+
+label: Resume rewind
+where: audio player → player settings; profile settings
+does: Rewinds playback a configured few seconds when you resume.
+also: Resume Rewind
+note: profile page spells it capitalized
+
+label: Reading Direction
+where: book detail → edit modal
+does: Chooses the direction pages advance (publisher convention — e.g. manga).
+
+label: Scan Info
+where: book detail page → info block
+does: Displays scanner-supplied notes attached to the item.
+also: Scan Information
+note: the editable form label in the modal reads "Scan Information"
+```