duplicates: perceptual hash + soft-mark resolution + upload 409

Adds pHash + dHash columns alongside the existing blake3 content_hash so
near-duplicates (re-encoded, resized, format-converted copies) become
queryable. /duplicates/{exact,perceptual} return groups; /duplicates/
{resolve,unresolve} flip a duplicate_of_hash soft-mark on losing rows
and union perceptual-only tag sets onto the survivor. The default
/photos listing filters duplicate_of_hash IS NULL so demoted siblings
stop cluttering the grid; include_duplicates=true opts back in for
Apollo's review modal. Upload now hashes bytes pre-write and returns
409 with the canonical sibling when a file's bytes already exist.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/database/models.rs

@@ -59,6 +59,10 @@ pub struct InsertImageExif {
     pub last_modified: i64,
     pub content_hash: Option<String>,
     pub size_bytes: Option<i64>,
+    /// 64-bit pHash (DCT) packed as i64. NULL for videos and decode failures.
+    pub phash_64: Option<i64>,
+    /// 64-bit dHash (gradient). NULL for videos and decode failures.
+    pub dhash_64: Option<i64>,
 }
 
 // Field order matches the post-migration column order in `image_exif`.
@@ -86,6 +90,14 @@ pub struct ImageExif {
     pub last_modified: i64,
     pub content_hash: Option<String>,
     pub size_bytes: Option<i64>,
+    pub phash_64: Option<i64>,
+    pub dhash_64: Option<i64>,
+    /// When non-null, this row is a soft-marked duplicate of the file
+    /// whose `content_hash` matches this value. The default `/photos`
+    /// listing filters such rows out.
+    pub duplicate_of_hash: Option<String>,
+    /// Unix seconds at which the resolve was committed.
+    pub duplicate_decided_at: Option<i64>,
 }
 
 #[derive(Insertable)]