fix(topdata): let pinned TLK ids evict stale state owners

The custom palette taxonomy (#46) pins display strings to fixed TLK
ids in tlk/custom.tlk.yml. registerInlineAtID demanded those ids be
free, but .tlk_state.json is a gitignored, per-machine cache: on any
machine built before #46, a ref could have dynamically grabbed a
now-pinned id (e.g. feat:yuanti/alternate_form.feat holding 2689),
failing the build with "TLK id N is already reserved by ...".

Make the pin authoritative over the cache: a stale cached owner on a
pinned id is evicted and reallocated a fresh id when next made active.
Only two pins fighting over one id in custom.tlk.yml is now an error.
This self-heals on the next build without deleting the state file.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/topdata/tlk_native.go

@@ -109,6 +109,7 @@ type tlkCompiler struct {
 	active       map[string]tlkEntryData
 	activeKeys   map[string]struct{}
 	reservedByID map[int]string
+	pinnedByID   map[int]string
 	nextID       int
 }
 
@@ -158,6 +159,7 @@ func newTLKCompiler(sourceDir string, legacy *legacyTLKData) (*tlkCompiler, erro
 		active:       map[string]tlkEntryData{},
 		activeKeys:   map[string]struct{}{},
 		reservedByID: reserved,
+		pinnedByID:   map[int]string{},
 		nextID:       nextID,
 	}
 	if legacy != nil {
@@ -380,12 +382,24 @@ func (c *tlkCompiler) registerInlineAtID(key string, id int, entry tlkEntryData)
 	if id < 0 {
 		return fmt.Errorf("TLK key %q has negative id %d", key, id)
 	}
+	// The pin is authoritative over the per-machine .tlk_state.json cache: a
+	// stale mapping that dynamically grabbed this id on an older build must
+	// yield so the pinned key can take it. Only a genuine clash between two
+	// pins in custom.tlk.yml is an author error.
+	if owner, ok := c.pinnedByID[id]; ok && owner != key {
+		return fmt.Errorf("TLK id %d is pinned by both %q and %q", id, owner, key)
+	}
 	if mapping, ok := c.state.Entries[key]; ok && mapping.ID != id {
-		return fmt.Errorf("TLK key %q changed id from %d to %d", key, mapping.ID, id)
+		// This key held a different cached id; release it so the pin wins.
+		if c.reservedByID[mapping.ID] == key {
+			delete(c.reservedByID, mapping.ID)
+		}
 	}
 	if owner, ok := c.reservedByID[id]; ok && owner != key {
-		return fmt.Errorf("TLK id %d is already reserved by %q", id, owner)
+		// Evict the stale owner; it gets a fresh id when next made active.
+		delete(c.state.Entries, owner)
 	}
+	c.pinnedByID[id] = key
 	c.state.Entries[key] = tlkStateMapping{ID: id}
 	c.reservedByID[id] = key
 	return c.markActive(key, entry)