capsules/fonts: JetBrainsMono-Regular.ttf as a raw-blob capsule (item 4.3.7b)

mkcapsule.c already ingests arbitrary non-.4th files as raw byte blobs
(validate_forth_blocks only applies to .4th filenames), so no hex/base64
text-encoding or tool changes are needed -- corrects the design premise
in FABRIC.md's 4.3.7b item text (see the FABRIC.md correction note this
commit carries). ttf_load_from_capsule() resolves the font capsule by
name, validates its content hash, and points ttf_font_t at the capsule
arena bytes directly, zero-copy.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

include/starkernel/ttf.h

@@ -182,6 +182,33 @@ typedef struct {
  */
 int ttf_glyph_outline(const ttf_font_t *font, uint32_t glyph_index, ttf_outline_t *out);
 
+#ifdef __STARKERNEL__
+#include "capsule.h"
+
+/**
+ * ttf_load_from_capsule - Resolve a font capsule by name and parse it,
+ * zero-copy (FABRIC.md item 4.3.7b). `out` borrows the capsule payload
+ * directly from `arena` — no kmalloc, no decode step, since the capsule
+ * is already a raw-byte match of the source `.ttf` (see
+ * capsules/fonts/README.md and FABRIC.md §27.7's 2026-08-10 correction:
+ * capsule storage needs no hex/base64 text-encoding, `tools/mkcapsule.c`
+ * already embeds arbitrary files as raw bytes). Validates the capsule's
+ * content hash (`capsule_validate(..., verify_hash=1)`) before parsing.
+ *
+ * @param capsule_name  Colon-separated capsule name, e.g.
+ *                       "fonts:JetBrainsMono-Regular.ttf"
+ * @return TTF_OK, TTF_ERR_TABLE_MISSING if the capsule isn't found, or a
+ *         capsule-validation/ttf_parse TTF_ERR_* code
+ */
+int ttf_load_from_capsule(
+    const CapsuleDirHeader *dir,
+    const CapsuleDesc *descs,
+    const CapsuleNameEntry *names,
+    const uint8_t *arena,
+    const char *capsule_name,
+    ttf_font_t *out);
+#endif /* __STARKERNEL__ */
+
 #ifdef __cplusplus
 }
 #endif